Try to make coverage report name unique across workflow runs

Author: steppi

.github/workflows/tests.yml

@@ -38,5 +38,5 @@ jobs:
       - name: Upload HTML coverage report
         uses: actions/upload-artifact@b4b15b8c7c6ac21ea08fcf65892d2ee8f75cf882  # v4.4.3
         with:
-          name: cov-html
+          name: cov-html-${{ matrix.runs-on }}
           path: build/coverage_report/**