Update dependency flutter_lints to v6

pubspec.yaml

@@ -41,7 +41,7 @@ dependencies:
   powersync: ^1.12.2
   uuid: ^4.5.1
   supabase_flutter: ^2.8.4
-  google_sign_in: 7.2.0
+  google_sign_in: ^6.3.0
   go_router: ^15.0.0
   smooth_page_indicator: ^1.2.1
   flutter_google_places_sdk: ^0.4.2+1
@@ -55,7 +55,7 @@ dev_dependencies:
   # activated in the `analysis_options.yaml` file located at the root of your
   # package. See that file for information about deactivating specific lint
   # rules and activating additional ones.
-  flutter_lints: ^5.0.0
+  flutter_lints: 6.0.0
 
 # For information on the generic Dart part of this file, see the
 # following page: https://dart.dev/tools/pub/pubspec