Bump actions/upload-artifact from 5 to 6

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

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

Signed-off-by: dependabot[bot] <support@github.com>

.github/workflows/ci.yml

@@ -87,7 +87,7 @@ jobs:
         run: twine check dist/*
 
       - name: Upload build artifacts
-        uses: actions/upload-artifact@v5
+        uses: actions/upload-artifact@v6
         with:
           name: dist
           path: dist/
@@ -245,7 +245,7 @@ jobs:
           Compress-Archive -Path * -DestinationPath ../tzst-${{ steps.version.outputs.version }}-${{ matrix.os_name }}-${{ matrix.arch }}.zip
 
       - name: Upload binary artifacts
-        uses: actions/upload-artifact@v5
+        uses: actions/upload-artifact@v6
         with:
           name: binary-${{ matrix.os_name }}-${{ matrix.arch }}
           path: tzst-${{ steps.version.outputs.version }}-${{ matrix.os_name }}-${{ matrix.arch }}.zip

.github/workflows/publish-docs.yml

@@ -56,7 +56,7 @@ jobs:
           python -m sphinx -b html . _build -W --keep-going
 
       - name: Upload documentation artifacts
-        uses: actions/upload-artifact@v5
+        uses: actions/upload-artifact@v6
         with:
           name: documentation
           path: docs/_build/