Also avoid double Gradle wrapper validation

.github/workflows/gradle-wrapper-validation.yml

@@ -1,6 +1,12 @@
 name: "Validate Gradle Wrapper"
-on: [push, pull_request]
-
+on:
+  push:
+    branches:
+      - main
+      - 'r5.*'
+  pull_request:
+    branches:
+      - '*'
 jobs:
   validation:
     name: "Validation"