Loosen constraint on web dependency to ease transition to 1.0.0 (#118)

Author: Rexios80

flutter_web_auth_2/pubspec.yaml

@@ -32,7 +32,7 @@ dependencies:
     sdk: flutter
   path_provider: ^2.1.2
   url_launcher: ^6.1.6
-  web: ^1.0.0
+  web: ">=0.5.0 <2.0.0"
   window_to_front: ^0.0.3
 
 dev_dependencies: