Pump intl library version to 0.20.0 (#733)

A small change to pump the intl library version to 0.20.0

Author: adelkhayata76

pubspec.yaml

@@ -14,7 +14,7 @@ dependencies:
   flutter:
     sdk: flutter
   shared_preferences: '>=2.0.0 <3.0.0'
-  intl: '>=0.17.0-0 <=0.19.0'
+  intl: '>=0.17.0-0 <=0.20.0'
   args: ^2.3.1
   path: ^1.8.1
   easy_logger: ^0.0.2