chore(package): update eslint to version 6.7.1

Closes #335

Author: greenkeeper[bot]

package.json

@@ -59,7 +59,7 @@
     "core-js": "^2.4.1",
     "cross-env": "^5.0.1",
     "css-loader": "^0.28.0",
-    "eslint": "^4.1.0",
+    "eslint": "^6.7.1",
     "eslint-plugin-jest": "^21.7.1",
     "eslint-plugin-react": "^7.0.0",
     "extract-text-webpack-plugin": "^3.0.0",