Remove grunt-clean

Author: kpdecker

package.json

@@ -57,7 +57,6 @@
     "eslint": "^5.12.0",
     "grunt": "^1.0.3",
     "grunt-babel": "^8.0.0",
-    "grunt-clean": "^0.4.0",
     "grunt-cli": "^1.3.2",
     "grunt-contrib-clean": "^2.0.0",
     "grunt-contrib-copy": "^1.0.0",