Bump the actions group with 3 updates (#325)

Bumps the actions group with 3 updates: [actions/checkout](https://github.com/actions/checkout), [actions/setup-python](https://github.com/actions/setup-python) and [actions/upload-artifact](https://github.com/actions/upload-artifact).


Updates `actions/checkout` from 4 to 6
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v4...v6)

Updates `actions/setup-python` from 5 to 6
- [Release notes](https://github.com/actions/setup-python/releases)
- [Commits](actions/setup-python@v5...v6)

Updates `actions/upload-artifact` from 4 to 6
- [Release notes](https://github.com/actions/upload-artifact/releases)
- [Commits](actions/upload-artifact@v4...v6)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: actions
- dependency-name: actions/setup-python
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: actions
- dependency-name: actions/upload-artifact
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: actions
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

.github/workflows/test.yml

@@ -15,10 +15,10 @@ jobs:
     name: Integration test
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v6
       with:
         persist-credentials: false
-    - uses: actions/setup-python@v5
+    - uses: actions/setup-python@v6
       with:
         python-version: "3.13"
 
@@ -40,7 +40,7 @@ jobs:
         --branches 3.14
 
     - name: Upload documentation
-      uses: actions/upload-artifact@v4
+      uses: actions/upload-artifact@v6
       with:
         name: www-root
         path: ./www
@@ -56,12 +56,12 @@ jobs:
         os: [windows-latest, macos-latest, ubuntu-latest]
 
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v6
       with:
         persist-credentials: false
 
     - name: Set up Python ${{ matrix.python-version }}
-      uses: actions/setup-python@v5
+      uses: actions/setup-python@v6
       with:
         python-version: ${{ matrix.python-version }}
         allow-prereleases: true