Bump actions/upload-artifact from 4 to 6

Bumps [actions/upload-artifact](https://github.com/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/upload-artifact
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

.github/workflows/build.yml

@@ -16,7 +16,7 @@ jobs:
       - name: Build wheel with hatch
         run: docker run --rm --entrypoint hatch -v "${{ github.workspace }}:/app" shell:hatch build
       - name: Upload wheel
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v6
         with:
           name: wheel
           path: dist/*.whl

.github/workflows/pytest.yml

@@ -17,7 +17,7 @@ jobs:
         run: docker run --rm -e HATCH_ENV=test -v "${{ github.workspace }}:/app" shell:hatch cov
 
       - name: Upload coverage artifact
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v6
         with:
           name: coverage-xml
           path: ${{ github.workspace }}/coverage.xml