fix(package): update npm to version 6.10.0

Closes #266

Author: greenkeeper[bot]

package.json

@@ -74,7 +74,7 @@
     "moment": "^2.20.1",
     "multi-glob": "^1.0.1",
     "ncp": "^2.0.0",
-    "npm": "^5.6.0",
+    "npm": "^6.10.0",
     "opn": "^5.1.0",
     "password-hash": "^1.2.2",
     "promised-handlebars-gottwik": "^2.0.1",