Update Codecov config after v5 update

Author: Jean85

.github/workflows/tests.yaml

@@ -64,6 +64,6 @@ jobs:
       - name: Upload code coverage
         uses: codecov/codecov-action@v5
         with:
-          file: './coverage.xml'
+          files: './coverage.xml'
           fail_ci_if_error: true
           token: ${{ secrets.CODECOV_TOKEN }}