Pin GitHub Actions to SHA for security

Update official GitHub Actions (actions/*, github/*) to use pinned
commit SHAs instead of version tags. This satisfies zizmor's
unpinned-action-reference security check.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: oschwald

.github/workflows/codeql-analysis.yml

@@ -18,7 +18,7 @@ jobs:
 
     steps:
     - name: Checkout repository
-      uses: actions/checkout@v6
+      uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
       with:
         # We must fetch at least the immediate parents so that if this is
         # a pull request then we can checkout the head.
@@ -32,15 +32,15 @@ jobs:
 
     # Initializes the CodeQL tools for scanning.
     - name: Initialize CodeQL
-      uses: github/codeql-action/init@v4
+      uses: github/codeql-action/init@5d4e8d1aca955e8d8589aabd499c5cae939e33c7 # v4.31.9
       # Override language selection by uncommenting this and choosing your languages
       # with:
       #   languages: go, javascript, csharp, python, cpp, java
 
     # Autobuild attempts to build any compiled languages  (C/C++, C#, or Java).
     # If this step fails, then you should remove it and run the build manually (see below)
     - name: Autobuild
-      uses: github/codeql-action/autobuild@v4
+      uses: github/codeql-action/autobuild@5d4e8d1aca955e8d8589aabd499c5cae939e33c7 # v4.31.9
 
     # ℹ️ Command-line programs to run using the OS shell.
     # 📚 https://git.io/JvXDl
@@ -54,4 +54,4 @@ jobs:
     #   make release
 
     - name: Perform CodeQL Analysis
-      uses: github/codeql-action/analyze@v4
+      uses: github/codeql-action/analyze@5d4e8d1aca955e8d8589aabd499c5cae939e33c7 # v4.31.9

.github/workflows/release.yml

@@ -17,7 +17,7 @@ jobs:
     name: Build source distribution
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
         with:
           submodules: true
           persist-credentials: false
@@ -28,7 +28,7 @@ jobs:
       - name: Build
         run: uv build
 
-      - uses: actions/upload-artifact@v6
+      - uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         with:
           path: |
             dist/*.tar.gz
@@ -42,7 +42,7 @@ jobs:
       id-token: write
     if: github.event_name == 'release' && github.event.action == 'published'
     steps:
-      - uses: actions/download-artifact@v7
+      - uses: actions/download-artifact@37930b1c2abaa49bbe596cd826c3c89aef350131 # v7.0.0
         with:
           name: artifact
           path: dist

.github/workflows/test.yml

@@ -18,7 +18,7 @@ jobs:
         env: ["3.10", 3.11, 3.12, 3.13, 3.14]
         os: [ubuntu-latest, ubuntu-24.04-arm, macos-latest, windows-latest]
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
         with:
           submodules: true
           persist-credentials: false

.github/workflows/zizmor.yml

@@ -15,7 +15,7 @@ jobs:
       security-events: write
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v6
+        uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
         with:
           persist-credentials: false