fix(ci): use fixed version of simple_spell_checker to fix CI warnings

Author: EchoEllet

example/pubspec.yaml

@@ -22,7 +22,7 @@ dependencies:
   equatable: ^2.0.5
   cross_file: ^0.3.4
   cached_network_image: ^3.3.1
-  simple_spell_checker: ^1.2.1
+  simple_spell_checker: 1.2.1
 
   # Bloc libraries
   bloc: ^8.1.4