chore: fix make generate-with-runner

Author: lcdsmao

Makefile

@@ -29,7 +29,7 @@ generate-with-command:
 	dart packages/command/bin/flutter_gen_command.dart --config example/pubspec.yaml
 
 generate-with-runner:
-	cd example && flutter packages pub run build_runner build --delete-conflicting-outputs && cd ..
+	cd example && flutter pub run build_runner build --delete-conflicting-outputs && cd ..
 
 unit-test:
 	cd packages/core/ && dart run test && cd ..