chore(package): update eslint to version 6.7.0

Closes #78

Author: greenkeeper[bot]

package.json

@@ -32,7 +32,7 @@
     "babel-preset-stage-1": "^6.22.0",
     "chai": "^4.0.1",
     "css-loader": "^0.28.0",
-    "eslint": "^4.1.1",
+    "eslint": "^6.7.0",
     "eslint-config-airbnb": "^15.0.0",
     "eslint-import-resolver-webpack": "^0.8.1",
     "eslint-loader": "^1.6.1",