Add workflow_dispatch trigger to gradle.yml

Author: cartland

.github/workflows/gradle.yml

@@ -1,6 +1,7 @@
 name: Gradle Build and Test
 
 on:
+  workflow_dispatch:
   push:
     branches: [main]
   pull_request:
@@ -19,4 +20,4 @@ jobs:
       - name: Build
         run: ./gradlew build
       - name: Test
-        run: ./gradlew test
+        run: ./gradlew test