remove upper constraint per flutter/flutter#68143

Author: Illia Romanenko

flutter_vlc_player_platform_interface/pubspec.yaml

@@ -5,7 +5,7 @@ version: 1.0.4
 
 environment:
   sdk: ">=2.10.0 <3.0.0"
-  flutter: ">=1.10.0 <2.0.0"
+  flutter: ">=1.10.0"
 
 dependencies:
   flutter: