Update ci.yml

Author: elect86

.github/workflows/ci.yml

@@ -8,9 +8,15 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@master
+    - uses: actions/checkout@v2
+    - name: Set up JDK 1.11
+      uses: actions/setup-java@v1
       with:
         java-version: openjdk@1.11
+    - name: Grant execute permission for gradlew
+      run: chmod +x gradlew
+    - name: Build with Gradle
+      run: ./gradlew build
 
   windows: 
     name: 'Windows'