Resolve "Use flutter linter and apply lints"

Closes #66 (closed)

pubspec.yaml

 name: puzzlegame
 description: A puzzle game application.
 publish_to: 'none'
-version: 1.0.0+1
+version: 0.0.58+58
 
 environment:
   sdk: '^3.0.0'
@@ -12,6 +12,9 @@ dependencies:
   image: ^4.1.3
   provider: ^6.0.5
 
+dev_dependencies:
+  flutter_lints: ^3.0.1
+
 flutter:
   uses-material-design: true
   assets: