Allow latest pkg:analyzer, prepare pkg:json_serializable v6.1.3 (#1069)

Author: kevmoo

json_serializable/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 6.1.3
+
+- Allow latest `package:analyzer`.
+
 ## 6.1.2
 
 - Fix issue with nested generics and `genericArgumentFactories: true`.

json_serializable/pubspec.yaml

@@ -8,7 +8,7 @@ environment:
   sdk: '>=2.14.0 <3.0.0'
 
 dependencies:
-  analyzer: ^2.0.0
+  analyzer: '>=2.0.0 <4.0.0'
   async: ^2.8.0
   build: ^2.0.0
   build_config: '>=0.4.4 <2.0.0'