Update dependency intl to ^0.20.0

Author: renovate[bot]

pubspec.yaml

@@ -12,7 +12,7 @@ dependencies:
   cupertino_icons: ^1.0.2
   built_value: ^8.0.0
   path_provider: ^2.0.1
-  intl: ^0.17.0
+  intl: ^0.20.0
   url_launcher: ^6.0.2
   built_collection: ^5.0.0
   collection: ^1.15.0