add np as devDeps

Author: afc163

package.json

@@ -51,6 +51,7 @@
     "father": "^2.22.0",
     "fs-extra": "^9.0.0",
     "gh-pages": "^3.0.0",
+    "np": "^6.5.0",
     "raf": "^3.4.0",
     "rc-tools": "8.x",
     "react": "^16.0.0",