Use published source_gen, refs for source_gen_test and source_helper.

Author: davidmorgan

json_serializable/pubspec.yaml

@@ -28,7 +28,7 @@ dependencies:
   path: ^1.9.0
   pub_semver: ^2.1.4
   pubspec_parse: ^1.0.0
-  source_gen: ^2.0.0
+  source_gen: ^3.0.0-dev
   source_helper: ^1.3.4
 
 dev_dependencies:
@@ -38,20 +38,18 @@ dev_dependencies:
   build_verify: ^3.0.0
   collection: ^1.17.0
   logging: ^1.0.0
-  source_gen_test: ^1.0.6
+  source_gen_test: ^1.2.0-dev
   test: ^1.24.4
   test_descriptor: ^2.0.0
   test_process: ^2.0.0
   yaml: ^3.0.0
 
 dependency_overrides:
-  build: ^3.0.0-dev
-  source_gen:
-    git:
-      url: https://github.com/dart-lang/source_gen
-      path: source_gen
-      ref: 6c9702e7152e61b16c8adec3f3011bda738b0e29
   source_gen_test:
     git:
       url: https://github.com/kevmoo/source_gen_test
-      ref: 9036882e5d69620fa387c14e880ebbe19ed99fee
+      ref: 8523d28a792cf2da9a3264ebe184b0ab64831fe0
+  source_helper:
+    git:
+      url: https://github.com/google/source_helper.dart
+      ref: 8adebf1a6b18f5673157ab450e63cc7329c39e10