Use Java 16 release instead of EA for GH actions, see #10

.github/workflows/test.yaml

@@ -17,6 +17,6 @@ jobs:
       - name: Set up JDK 16
         uses: actions/setup-java@v1
         with:
-          java-version: 16-ea
+          java-version: 16
       - name: Test on Java 16
         run: ./gradlew common:test -Dorg.gradle.jvmargs=--illegal-access=warn --rerun-tasks