chore(package): update pify to version 4.0.0

Author: greenkeeper[bot]

package.json

@@ -155,7 +155,7 @@
     "junk": "2.1.0",
     "minimist": "1.2.0",
     "mkdirp": "0.5.1",
-    "pify": "3.0.0",
+    "pify": "4.0.0",
     "prettier": "1.14.0",
     "pretty-bytes": "5.1.0",
     "pretty-quick": "1.6.0",