chore(package): update eslint to version 6.7.1

Closes #35

Author: greenkeeper[bot]

package.json

@@ -43,7 +43,7 @@
   "devDependencies": {
     "ava": "^2.0.0",
     "coveralls": "^3.0.2",
-    "eslint": "^5.14.0",
+    "eslint": "^6.7.1",
     "eslint-config-prettier": "^6.1.0",
     "husky": "^2.0.0",
     "lint-staged": "^9.0.0",