Update eslint to version 6.5.0

Closes #6

Author: greenkeeper[bot]

package.json

@@ -26,7 +26,7 @@
   "devDependencies": {
     "@tailify/eslint-config-legacy": "^2.0.0",
     "@tailify/prettier-config": "^1.0.0",
-    "eslint": "^5.10.0",
+    "eslint": "^6.5.0",
     "jest": "^24.7.0",
     "postcss": "^7.0.0",
     "postcss-load-config": "^2.0.0",