fix bad merge - analyzer constraint (#761)

Author: kevmoo

json_serializable/pubspec.yaml

@@ -8,7 +8,7 @@ environment:
   sdk: '>=2.11.0 <3.0.0'
 
 dependencies:
-  analyzer: ^0.40.6
+  analyzer: '>=0.40.6 <0.42.0'
   build: '>=0.12.6 <2.0.0'
   build_config: '>=0.2.6 <0.5.0'