sdk constraint updated (#253)

Author: diegoveloper

pubspec.yaml

@@ -5,7 +5,7 @@ homepage: https://github.com/diegoveloper/
 repository: https://github.com/diegoveloper/flutter_keyboard_actions/
 
 environment:
-  sdk: '>=2.17.0 <3.0.0'
+  sdk: '>=2.17.0 <4.0.0'
 
 dependencies:
   flutter: