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/tests.yml

@@ -112,7 +112,7 @@ jobs:
 
     - name: Upload Test Results
       if: always()
-      uses: actions/upload-artifact@v5
+      uses: actions/upload-artifact@v6
       with:
         name: Test Results (PHP ${{ matrix.php-versions }})
         path: tst/results.xml
@@ -203,7 +203,7 @@ jobs:
 
     - name: Upload Test Results
       if: always()
-      uses: actions/upload-artifact@v5
+      uses: actions/upload-artifact@v6
       with:
         name: Test Results
         path: tst/results.xml
@@ -235,7 +235,7 @@ jobs:
 
     - name: Upload Test Results
       if: always()
-      uses: actions/upload-artifact@v5
+      uses: actions/upload-artifact@v6
       with:
         name: Test Results (Mocha)
         path: js/mocha-results.xml
@@ -245,7 +245,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - name: Upload
-      uses: actions/upload-artifact@v5
+      uses: actions/upload-artifact@v6
       with:
         name: Event File
         path: "${{ github.event_path }}"