update amplify_flutter dep to >=0.3.0 <0.5.0 (#1361)

Author: Jordan-Nelson

packages/amplify_authenticator/pubspec.yaml

@@ -8,10 +8,10 @@ environment:
   flutter: ">=1.17.0"
 
 dependencies:
-  amplify_auth_cognito: ^0.3.0
-  amplify_auth_plugin_interface: ^0.3.0
-  amplify_core: ^0.3.0
-  amplify_flutter: ^0.3.0
+  amplify_auth_cognito: ">=0.3.0 <0.5.0"
+  amplify_auth_plugin_interface: ">=0.3.0 <0.5.0"
+  amplify_core: ">=0.3.0 <0.5.0"
+  amplify_flutter: ">=0.3.0 <0.5.0"
   collection: ^1.15.0
   flutter:
     sdk: flutter