diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index ee8bdd870..9fcf0ca52 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -69,7 +69,7 @@ jobs:
     runs-on: ${{ matrix.runs-on }}
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
 
     - name: Setup Python ${{ matrix.python }}
       uses: actions/setup-python@v4
@@ -205,7 +205,7 @@ jobs:
     runs-on: ubuntu-20.04
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
 
     - name: Setup Python ${{ matrix.python-version }} (deadsnakes)
       uses: deadsnakes/action@v3.0.1
@@ -310,7 +310,7 @@ jobs:
     container: "silkeh/clang:${{ matrix.clang }}${{ matrix.container_suffix }}"
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
 
     - name: Add wget and python3
       run: apt-get update && apt-get install -y python3-dev python3-numpy python3-pytest libeigen3-dev
@@ -344,7 +344,7 @@ jobs:
     container: nvidia/cuda:12.2.0-devel-ubuntu22.04
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
 
     # tzdata will try to ask for the timezone, so set the DEBIAN_FRONTEND
     - name: Install 🐍 3
@@ -368,7 +368,7 @@ jobs:
 #    container: centos:8
 #
 #    steps:
-#    - uses: actions/checkout@v3
+#    - uses: actions/checkout@v4
 #
 #    - name: Add Python 3 and a few requirements
 #      run: yum update -y && yum install -y git python3-devel python3-numpy python3-pytest make environment-modules
@@ -413,7 +413,7 @@ jobs:
       # tzdata will try to ask for the timezone, so set the DEBIAN_FRONTEND
       DEBIAN_FRONTEND: 'noninteractive'
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
 
     - name: Add NVHPC Repo
       run: |
@@ -475,7 +475,7 @@ jobs:
     container: "gcc:${{ matrix.gcc }}"
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
 
     - name: Add Python 3
       run: apt-get update; apt-get install -y python3-dev python3-numpy python3-pytest python3-pip libeigen3-dev
@@ -535,7 +535,7 @@ jobs:
     name: "🐍 3 • ICC latest • x64"
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
 
     - name: Add apt repo
       run: |
@@ -639,7 +639,13 @@ jobs:
     container: "${{ matrix.container }}"
 
     steps:
-    - uses: actions/checkout@v3
+    - name: Latest actions/checkout
+      uses: actions/checkout@v4
+      if: matrix.container != 'centos:7'
+
+    - name: Pin actions/checkout as required for centos:7
+      uses: actions/checkout@v3
+      if: matrix.container == 'centos:7'
 
     - name: Add Python 3 (RHEL 7)
       if: matrix.container == 'centos:7'
@@ -687,7 +693,7 @@ jobs:
     container: i386/debian:buster
 
     steps:
-    - uses: actions/checkout@v1  # Required to run inside docker
+    - uses: actions/checkout@v1  # v1 is required to run inside docker
 
     - name: Install requirements
       run: |
@@ -730,7 +736,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
 
     - uses: actions/setup-python@v4
       with:
@@ -782,7 +788,7 @@ jobs:
     runs-on: windows-2019
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
 
     - name: Setup Python ${{ matrix.python }}
       uses: actions/setup-python@v4
@@ -835,7 +841,7 @@ jobs:
     runs-on: windows-2019
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
 
     - name: Setup Python ${{ matrix.python }}
       uses: actions/setup-python@v4
@@ -883,7 +889,7 @@ jobs:
     runs-on: windows-2022
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
 
     - name: Setup Python ${{ matrix.python }}
       uses: actions/setup-python@v4
@@ -961,7 +967,7 @@ jobs:
           mingw-w64-${{matrix.env}}-boost
           mingw-w64-${{matrix.env}}-catch
 
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
 
     - name: Configure C++11
       # LTO leads to many undefined reference like
@@ -1032,7 +1038,7 @@ jobs:
         run: env
 
       - name: Checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Set up Clang
         uses: egor-tensin/setup-clang@v1
@@ -1101,7 +1107,7 @@ jobs:
         run: env
 
       - name: Checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Show Clang++ version before brew install llvm
         run: clang++ --version
diff --git a/.github/workflows/configure.yml b/.github/workflows/configure.yml
index ec7cd612d..a49d8d252 100644
--- a/.github/workflows/configure.yml
+++ b/.github/workflows/configure.yml
@@ -49,7 +49,7 @@ jobs:
     runs-on: ${{ matrix.runs-on }}
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
 
     - name: Setup Python 3.7
       uses: actions/setup-python@v4
diff --git a/.github/workflows/format.yml b/.github/workflows/format.yml
index b8242ee52..9b2da5944 100644
--- a/.github/workflows/format.yml
+++ b/.github/workflows/format.yml
@@ -25,7 +25,7 @@ jobs:
     name: Format
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - uses: actions/setup-python@v4
       with:
         python-version: "3.x"
@@ -43,7 +43,7 @@ jobs:
     runs-on: ubuntu-latest
     container: silkeh/clang:15-bullseye
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
 
     - name: Install requirements
       run: apt-get update && apt-get install -y git python3-dev python3-pytest
diff --git a/.github/workflows/pip.yml b/.github/workflows/pip.yml
index d6687b441..5bc7c4b9c 100644
--- a/.github/workflows/pip.yml
+++ b/.github/workflows/pip.yml
@@ -28,7 +28,7 @@ jobs:
     runs-on: windows-latest
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
 
     - name: Setup 🐍 3.6
       uses: actions/setup-python@v4
@@ -50,7 +50,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
 
     - name: Setup 🐍 3.8
       uses: actions/setup-python@v4
diff --git a/.github/workflows/upstream.yml b/.github/workflows/upstream.yml
index dd8a1c960..5d893cd85 100644
--- a/.github/workflows/upstream.yml
+++ b/.github/workflows/upstream.yml
@@ -25,7 +25,7 @@ jobs:
     if: "contains(github.event.pull_request.labels.*.name, 'python dev')"
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
 
     - name: Setup Python 3.12
       uses: actions/setup-python@v4