chore: Prevent duplicate builds for PRs from base repo branches (#1496)

Author: valfirst

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

@@ -1,5 +1,12 @@
 name: "Validate Gradle Wrapper"
-on: [push, pull_request]
+
+on:
+  push:
+    branches:
+    - master
+  pull_request:
+    branches:
+    - master
 
 jobs:
   validation:

.github/workflows/gradle.yml

@@ -1,6 +1,12 @@
 name: Appium Java Client CI
 
-on: [push, pull_request]
+on:
+  push:
+    branches:
+    - master
+  pull_request:
+    branches:
+    - master
 
 jobs:
   build: