fix dart_webrtc dependency constraint

Author: Brazol

pubspec.yaml

@@ -8,7 +8,7 @@ environment:
 
 dependencies:
   collection: ^1.17.0
-  dart_webrtc: ">=1.4.0 <1.5.3"
+  dart_webrtc: ">=1.4.0 <1.6.0"
   flutter:
     sdk: flutter
   path_provider: ^2.0.2