chore: update GitHub Actions to latest major versions (#879)

- actions/checkout v5 -> v7
- actions/setup-python v6 -> v7
- actions/configure-pages v5 -> v6
- actions/upload-pages-artifact v3 -> v5
- actions/deploy-pages v4 -> v5
- actions/upload-artifact v4 -> v7
- actions/download-artifact v4 -> v8
- docker/setup-qemu-action v3 -> v4
- docker/setup-buildx-action v3 -> v4
- docker/metadata-action v5 -> v6
- docker/login-action v3 -> v4
- docker/build-push-action v6 -> v7
- codecov/codecov-action v5 -> v7
- peter-evans/create-pull-request v7 -> v8

codecov/test-results-action (already replaced by codecov-action with
report_type: test_results) and pypa/gh-action-pypi-publish@release/v1
(moving branch, still the current major) need no change.

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

.github/workflows/docs.yml

@@ -27,10 +27,10 @@ jobs:
       pages: write
       id-token: write
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v7
 
       - name: Set up Python
-        uses: actions/setup-python@v6
+        uses: actions/setup-python@v7
         with:
           python-version: "3.13"
           cache: pip
@@ -44,13 +44,13 @@ jobs:
         run: make -C docs html
 
       - name: Configure Pages
-        uses: actions/configure-pages@v5
+        uses: actions/configure-pages@v6
 
       - name: Upload Pages artifact
-        uses: actions/upload-pages-artifact@v3
+        uses: actions/upload-pages-artifact@v5
         with:
           path: docs/build/html
 
       - name: Deploy to GitHub Pages
         id: deployment
-        uses: actions/deploy-pages@v4
+        uses: actions/deploy-pages@v5