.github/workflows/xcop.yml in judges-0.20.0 vs .github/workflows/xcop.yml in judges-0.21.0

@@ -17,12 +17,16 @@
 # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 # SOFTWARE.
 ---
 name: xcop
-on:
+'on':
   push:
+    branches:
+      - master
   pull_request:
+    branches:
+      - master
 jobs:
   xcop:
     runs-on: ubuntu-22.04
     steps:
       - uses: actions/checkout@v4