change fcm build.grade

Author: jwfing

android-sdk/leancloud-fcm/build.gradle

@@ -66,7 +66,6 @@ dependencies {
     // When using the BoM, you don't specify versions in Firebase library dependencies
     implementation 'com.google.firebase:firebase-messaging'
 
-    implementation 'androidx.appcompat:appcompat:1.0.0'
     testImplementation 'junit:junit:4.12'
     androidTestImplementation 'androidx.test:runner:1.1.0'
     androidTestImplementation 'androidx.test.espresso:espresso-core:3.1.0'