Upgrade package:intl to 0.20.2 (#162591)

Run `flutter update-packages --cherry-pick-package intl
--cherry-pick-version 0.20.2`

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packages/flutter_localizations/pubspec.yaml

@@ -11,7 +11,7 @@ dependencies:
 
   flutter:
     sdk: flutter
-  intl: 0.19.0
+  intl: 0.20.2
 
   characters: 1.4.0 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
   clock: 1.1.2 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
@@ -40,4 +40,4 @@ dev_dependencies:
   test_api: 0.7.4 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
   vm_service: 15.0.0 # THIS LINE IS AUTOGENERATED - TO UPDATE USE "flutter update-packages --force-upgrade"
 
-# PUBSPEC CHECKSUM: 585c
+# PUBSPEC CHECKSUM: 0a56