chore: Update client common to use common library 1.2.1 (#169)

Author: kinyoklion

packages/common_client/pubspec.yaml

@@ -9,7 +9,7 @@ environment:
 
 dependencies:
   http: ^1.1.2
-  launchdarkly_dart_common: 1.2.0
+  launchdarkly_dart_common: 1.2.1
   launchdarkly_event_source_client: 1.0.0
   crypto: ^3.0.3
   uuid: ">= 3.0.7 <5.0.0"