Update ci.yaml

Author: Yozhef

.github/workflows/ci.yaml

@@ -77,5 +77,5 @@ jobs:
               if: matrix.coverage == 'xdebug'
               with:
                   token: ${{ secrets.CODECOV_TOKEN }}
-                  file: './coverage.xml'
+                  files: './coverage.xml'
                   fail_ci_if_error: true