chore: upgrade play-services-auth and remove unused imports (#2190)

Author: thatfiredev

auth/src/main/java/com/firebase/ui/auth/AuthUI.java

@@ -20,44 +20,33 @@
 import android.os.CancellationSignal;
 import android.os.Parcel;
 import android.os.Parcelable;
-import android.text.TextUtils;
 import android.util.Log;
 
 import com.facebook.login.LoginManager;
 import com.firebase.ui.auth.data.model.FlowParameters;
 import com.firebase.ui.auth.ui.idp.AuthMethodPickerActivity;
-import com.firebase.ui.auth.util.CredentialUtils;
 import com.firebase.ui.auth.util.ExtraConstants;
 import com.firebase.ui.auth.util.GoogleApiUtils;
 import com.firebase.ui.auth.util.Preconditions;
 import com.firebase.ui.auth.util.data.PhoneNumberUtils;
 import com.firebase.ui.auth.util.data.ProviderAvailability;
-import com.firebase.ui.auth.util.data.ProviderUtils;
-import com.google.android.gms.auth.api.identity.Identity;
-import com.google.android.gms.auth.api.signin.GoogleSignIn;
-import com.google.android.gms.auth.api.signin.GoogleSignInAccount;
 import com.google.android.gms.auth.api.signin.GoogleSignInOptions;
-import com.google.android.gms.common.api.ApiException;
 import com.google.android.gms.common.api.CommonStatusCodes;
 import com.google.android.gms.common.api.Scope;
 import com.google.android.gms.tasks.Task;
 import com.google.android.gms.tasks.TaskCompletionSource;
 import com.google.android.gms.tasks.Tasks;
 import com.google.firebase.FirebaseApp;
 import com.google.firebase.auth.ActionCodeSettings;
-import com.google.firebase.auth.AuthCredential;
-import com.google.firebase.auth.AuthResult;
 import com.google.firebase.auth.EmailAuthProvider;
 import com.google.firebase.auth.FacebookAuthProvider;
 import com.google.firebase.auth.FirebaseAuth;
 import com.google.firebase.auth.FirebaseAuthInvalidUserException;
-import com.google.firebase.auth.FirebaseAuthProvider;
 import com.google.firebase.auth.FirebaseUser;
 import com.google.firebase.auth.GithubAuthProvider;
 import com.google.firebase.auth.GoogleAuthProvider;
 import com.google.firebase.auth.PhoneAuthProvider;
 import com.google.firebase.auth.TwitterAuthProvider;
-import com.google.firebase.auth.UserInfo;
 
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;

buildSrc/src/main/kotlin/Config.kt

@@ -53,7 +53,7 @@ object Config {
         }
 
         object PlayServices {
-            const val auth = "com.google.android.gms:play-services-auth:20.3.0"
+            const val auth = "com.google.android.gms:play-services-auth:21.3.0"
         }
 
         object Provider {