Update ci.yml - use gradle instead of maven

Author: elisherer

.github/workflows/ci.yml

@@ -25,7 +25,7 @@ jobs:
         java-version: '17'
         distribution: 'temurin'
         java-package: jdk
-        cache: maven
+        cache: gradle
 
     - name: Setup Gradle
       uses: gradle/gradle-build-action@v2.4.2