ci: store test coverage data

Author: g105b

.github/workflows/ci.yml

@@ -59,6 +59,12 @@ jobs:
           php_extensions: xdebug
           configuration: phpunit.xml
 
+      - name: Store coverage data
+        uses: actions/upload-artifact@v4
+        with:
+          name: code-coverage-${{ matrix.php }}-${{ github.run_number }}
+          path: _coverage
+
   coverage:
     runs-on: ubuntu-latest
     needs: [ phpunit ]