refactor(pluginutils): improve readability of attachScopes test (#551)

Author: eight04

packages/pluginutils/package.json

@@ -58,6 +58,7 @@
     "@rollup/plugin-typescript": "^5.0.2",
     "@types/node": "^14.0.26",
     "@types/picomatch": "^2.2.1",
+    "acorn": "^8.0.4",
     "rollup": "^2.23.0"
   },
   "types": "types/index.d.ts",