Build CI with Java 8 and 11

Signed-off-by: Hannes Achleitner <hannes.software@gmx.at>

.github/workflows/assembleFlavors.yml

@@ -10,13 +10,15 @@ jobs:
         strategy:
             fail-fast: false
             matrix:
+                java_version: [ 8, 11 ]
                 flavor: [ Generic, Gplay ]
         steps:
             -   uses: actions/checkout@v2
-            -   name: set up JDK 1.8
-                uses: actions/setup-java@v1
+            -   name: set up JDK ${{ matrix.java_version }}
+                uses: actions/setup-java@v2
                 with:
-                    java-version: 1.8
+                    distribution: "adopt"
+                    java-version: ${{ matrix.java_version }}
             -   name: Build ${{ matrix.flavor }}
                 run: |
                     echo "org.gradle.jvmargs=-Xmx2g -XX:MaxMetaspaceSize=512m -XX:+HeapDumpOnOutOfMemoryError" >> gradle.properties