Update dependencies for the Dart Debug Extension (#1479)

Author: elliette

dwds/debug_extension/pubspec.yaml

@@ -18,8 +18,8 @@ dependencies:
 
 dev_dependencies:
   build: ^2.0.0
-  build_web_compilers: ">=1.2.0 <3.0.0"
-  build_runner: ">=1.5.0 <2.0.0"
+  build_web_compilers: ^3.0.0
+  build_runner: ^2.0.6
   built_collection: ^5.0.0
   dwds: ^11.0.0
   webdev: ^2.0.0