chore(package): update load-grunt-tasks to version 4.0.0

Author: greenkeeper[bot]

package.json

@@ -34,7 +34,7 @@
     "grunt-release-it": "^1.0.1",
     "jsdom": "^11.6.2",
     "jsdom-global": "^3.0.2",
-    "load-grunt-tasks": "^3.5.0",
+    "load-grunt-tasks": "^4.0.0",
     "mocha": "^5.0.0",
     "nyc": "^11.4.1",
     "unexpected": "^10.13.3"