ci: coverage for each php version

Author: Greg Bowler

.github/workflows/ci.yml

@@ -70,13 +70,16 @@ jobs:
   coverage:
     runs-on: ubuntu-latest
     needs: [ phpunit ]
+    strategy:
+      matrix:
+        php: [ 8.1, 8.2, 8.3, 8.4 ]
 
     steps:
       - uses: actions/checkout@v4
 
       - uses: actions/download-artifact@v4
         with:
-          name: code-coverage
+          name: code-coverage-${{ matrix.php }}-${{ github.run_number }}
           path: _coverage
 
       - name: Output coverage