chore(package): update eslint to version 6.7.0

Closes #48

Author: greenkeeper[bot]

package.json

@@ -41,7 +41,7 @@
     "clean-webpack-plugin": "^0.1.16",
     "copy-webpack-plugin": "^4.0.0",
     "css-loader": "^0.28.5",
-    "eslint": "^4.5.0",
+    "eslint": "^6.7.0",
     "eslint-config-prev": "^6.0.0",
     "extract-text-webpack-plugin": "^3.0.0",
     "gh-pages": "^1.0.0",