Update eslint to the latest version 🚀 (#1289)

* chore(package): update eslint to version 6.4.0

* chore(package): update lockfile package-lock.json

Author: greenkeeper[bot]

package-lock.json

@@ -83,7 +83,7 @@
     "core-js": "3.2.1",
     "cross-env": "5.2.1",
     "css-loader": "3.2.0",
-    "eslint": "6.3.0",
+    "eslint": "6.4.0",
     "eslint-plugin-jest": "22.17.0",
     "eslint-plugin-react": "7.14.3",
     "file-loader": "4.2.0",