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] <[email protected]>

Author: dependabot[bot]

.github/workflows/ci.yaml

@@ -202,7 +202,7 @@ jobs:
 
     - name: Upload coverage artifact
       if: always() && (steps.test.outcome == 'success' || steps.test.outcome == 'failure')
-      uses: actions/upload-artifact@v4
+      uses: actions/upload-artifact@v6
       with:
         include-hidden-files: true
         name: coverage-${{ matrix.plex }}-${{ steps.python.outputs.python-version }}

.github/workflows/pypi.yml

@@ -36,7 +36,7 @@ jobs:
         python -m twine check dist/*
 
     - name: Upload builds
-      uses: actions/upload-artifact@v4
+      uses: actions/upload-artifact@v6
       with:
         name: dist
         path: dist