Update dependency grunt-contrib-uglify to v5

Author: renovate-bot

package.json

@@ -19,7 +19,7 @@
     "jquery": "2.1.1",
     "grunt-contrib-jshint": "~0.10.0",
     "grunt-contrib-nodeunit": "~0.4.1",
-    "grunt-contrib-uglify": "~0.5.0",
+    "grunt-contrib-uglify": "~5.0.0",
     "grunt-contrib-clean": "~0.5.0",
     "grunt-contrib-watch": "~0.6.0",
     "grunt-contrib-copy": "~0.5.0"