update build workflow java version

.github/workflows/gradle.yml

@@ -16,10 +16,10 @@ jobs:
 
     steps:
     - uses: actions/checkout@v2
-    - name: Set up JDK 1.8
+    - name: Set up JDK 1.16
       uses: actions/setup-java@v1
       with:
-        java-version: 1.8
+        java-version: 1.16
     - name: Grant execute permission for gradlew
       run: chmod +x gradlew
     - name: Build with Gradle