Use JDK 11 for build workflow

.github/workflows/build_app.yml

@@ -32,10 +32,10 @@ jobs:
           fetch-depth: 0
           ref: ${{ github.event.inputs.git-ref }}
 
-      - name: Set up JDK 1.8
+      - name: Set up JDK 11
         uses: actions/setup-java@v1
         with:
-          java-version: 1.8
+          java-version: 11
 
       - name: Set up keystore
         run: mkdir -p ~/.android/ && echo "${{ secrets.DEBUG_KEYSTORE }}" | base64 --decode > ~/.android/debug.keystore