chore(package): update eslint to version 6.6.0

Closes #49

Author: greenkeeper[bot]

package.json

@@ -50,7 +50,7 @@
   "devDependencies": {
     "@colony/eslint-config-colony": "^7.0.0",
     "babel-eslint": "^10.0.1",
-    "eslint": "^5.8.0",
+    "eslint": "^6.6.0",
     "eslint-config-airbnb-base": "^13.1.0",
     "eslint-config-prettier": "^3.1.0",
     "eslint-plugin-flowtype": "^3.1.1",