Bump actions/setup-python from 5 to 6 (#12952)

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

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

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

.github/workflows/build.yml

@@ -14,7 +14,7 @@ jobs:
         with:
           enable-cache: true
           cache-dependency-glob: uv.lock
-      - uses: actions/setup-python@v5
+      - uses: actions/setup-python@v6
         with:
           python-version: 3.x
           allow-prereleases: true

.github/workflows/directory_writer.yml

@@ -9,7 +9,7 @@ jobs:
       - uses: actions/checkout@v5
         with:
           fetch-depth: 0
-      - uses: actions/setup-python@v5
+      - uses: actions/setup-python@v6
         with:
           python-version: 3.x
       - name: Write DIRECTORY.md

.github/workflows/project_euler.yml

@@ -16,7 +16,7 @@ jobs:
     steps:
       - uses: actions/checkout@v5
       - uses: astral-sh/setup-uv@v6
-      - uses: actions/setup-python@v5
+      - uses: actions/setup-python@v6
         with:
           python-version: 3.x
       - run: uv sync --group=euler-validate --group=test
@@ -26,7 +26,7 @@ jobs:
     steps:
       - uses: actions/checkout@v5
       - uses: astral-sh/setup-uv@v6
-      - uses: actions/setup-python@v5
+      - uses: actions/setup-python@v6
         with:
           python-version: 3.x
       - run: uv sync --group=euler-validate --group=test

.github/workflows/sphinx.yml

@@ -27,7 +27,7 @@ jobs:
     steps:
       - uses: actions/checkout@v5
       - uses: astral-sh/setup-uv@v6
-      - uses: actions/setup-python@v5
+      - uses: actions/setup-python@v6
         with:
           python-version: 3.13
           allow-prereleases: true