Upgrade gradle and gradle plugin.

.github/workflows/android.yml

@@ -14,11 +14,17 @@ jobs:
 
     steps:
     - uses: actions/checkout@v1
+
     - name: set up JDK 1.8
       uses: actions/setup-java@v1
       with:
         java-version: 1.8
+
+    - name: Install NDK
+      run: echo "y" | sudo /usr/local/lib/android/sdk/tools/bin/sdkmanager --install "ndk;20.0.5594570" --sdk_root=${ANDROID_SDK_ROOT}
+
     - name: Validate Gradle Wrapper
       uses: gradle/wrapper-validation-action@v1
+
     - name: Build with Gradle
       run: ./gradlew qa