chore: Upgrade dev dependencies

Author: Sander Beekhuis

package.json

@@ -41,16 +41,16 @@
     "tv4": "~1.2.7"
   },
   "devDependencies": {
-    "chai": "^3.5.0",
+    "chai": "^4.2.0",
     "grunt": "^1.0.1",
     "grunt-bump": "^0.8.0",
     "grunt-cli": "^1.2.0",
     "grunt-continue": "^0.1.0",
-    "grunt-contrib-jshint": "^1.0.0",
+    "grunt-contrib-jshint": "^2.1.0",
     "grunt-mocha": "^1.0.2",
     "grunt-mocha-test": "^0.13.2",
     "jshint-path-reporter": "^0.1.3",
-    "mocha": "^5.2.0",
+    "mocha": "^6.1.4",
     "mocha-unfunk-reporter": "^0.4.0",
     "requirejs": "^2.2.0"
   },