fix(package): update debug to version 4.1.1

Closes #88

Author: greenkeeper[bot]

package.json

@@ -164,7 +164,7 @@
   "main": "./index",
   "dependencies": {
     "chai": ">=1.9.2 <4.0.0",
-    "debug": "^2.6.8",
+    "debug": "^4.1.1",
     "deep-equal": "^1.0.0",
     "json-stringify-safe": "^5.0.1",
     "lodash": "~4.17.4",