Update example app firebase versions

Author: amrfarid140

firebase_auth_oauth/example/pubspec.yaml

@@ -8,8 +8,8 @@ environment:
 dependencies:
   flutter:
     sdk: flutter
-  firebase_auth: ^2.0.0
-  firebase_core: ^1.3.0
+  firebase_auth: ^3.0.1
+  firebase_core: ^1.4.0
 
   # The following adds the Cupertino Icons font to your application.
   # Use with the CupertinoIcons class for iOS style icons.