Set compileOptions compat for android build to java 1.8 to support flatbuffers 1.11 bytecode

android/build.gradle

@@ -29,6 +29,10 @@ android {
             proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
         }
     }
+    compileOptions {
+        sourceCompatibility 1.8
+        targetCompatibility 1.8
+    }
     productFlavors {
     }
 }