Use JDK 16 for workflows

Author: WalkerKnapp

.github/workflows/gradle.yml

@@ -9,10 +9,10 @@ jobs:
     steps:
     - uses: actions/checkout@v2
 
-    - name: Set up JDK 8
+    - name: Set up JDK 16
       uses: actions/setup-java@v1
       with:
-        java-version: 8
+        java-version: 16
 
     - name: Grant execute permission for gradlew
       run: chmod +x gradlew