Update dependency np to v6 (#23)

Author: renovate-bot

package.json

@@ -43,7 +43,7 @@
     "husky": "4.2.1",
     "lint-staged": "10.0.7",
     "magic-string": "0.25.6",
-    "np": "5.2.1",
+    "np": "6.0.0",
     "npm-run-all": "4.1.5",
     "prettier": "1.19.1",
     "rimraf": "3.0.1",