Fix lint

Author: lfkellogg

firebase-appdistribution/src/main/java/com/google/firebase/appdistribution/impl/ApkHashExtractor.java

@@ -20,7 +20,6 @@
 import android.content.pm.PackageInfo;
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
-import androidx.annotation.VisibleForTesting;
 import com.google.firebase.appdistribution.FirebaseAppDistributionException;
 import com.google.firebase.appdistribution.FirebaseAppDistributionException.Status;
 import java.io.File;