Bump actions/setup-python from 5 to 6 (#30409)

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/ci.yml

@@ -26,7 +26,7 @@ jobs:
           bash tools/ci/install_build_deps.sh
           bash tools/ci/install_dreamchecker.sh
 
-      - uses: actions/setup-python@v5
+      - uses: actions/setup-python@v6
         with:
           python-version: '3.11'
           cache: 'pip'
@@ -167,7 +167,7 @@ jobs:
     runs-on: windows-latest
     steps:
       - uses: actions/checkout@v5
-      - uses: actions/setup-python@v5
+      - uses: actions/setup-python@v6
         with:
           python-version: '3.8.2' # Script was made for 3.8.2
           architecture: 'x86' # This MUST be x86

.github/workflows/merge_upstream_master.yml

@@ -59,7 +59,7 @@ jobs:
           cache: 'yarn'
           cache-dependency-path: ./tgui/yarn.lock
 
-      - uses: actions/setup-python@v5
+      - uses: actions/setup-python@v6
         with:
           python-version: '3.11'
           cache: 'pip'