Add "Validate Gradle Wrapper" (gitlab4j#1186)

See gitlab4j#1166

Author: jmini

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

@@ -0,0 +1,10 @@
+name: "Validate Gradle Wrapper"
+on: [push, pull_request]
+
+jobs:
+  validation:
+    name: "Gradle wrapper validation"
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: gradle/actions/wrapper-validation@v4