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

Author: greenkeeper[bot]

package.json

@@ -37,7 +37,7 @@
     "grunt-postcss": "0.9.0",
     "grunt-sass": "2.1.0",
     "grunt-sass-lint": "0.2.4",
-    "load-grunt-tasks": "~3.5",
+    "load-grunt-tasks": "~4.0.0",
     "node-sass": "4.9.0",
     "sass-lint": "1.12.1",
     "uglify-save-license": "0.4.1"