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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dev/bots/pubspec.yaml

@@ -8,7 +8,7 @@ dependencies:
   analyzer: 6.11.0
   args: 2.6.0
   crypto: 3.0.6
-  intl: 0.19.0
+  intl: 0.20.2
   file: 7.0.1
   flutter_devicelab:
     path: ../devicelab
@@ -77,4 +77,4 @@ dependencies:
 dev_dependencies:
   test_api: 0.7.4
 
-# PUBSPEC CHECKSUM: fb9d
+# PUBSPEC CHECKSUM: 5997