chore(package): update eslint to version 6.2.0

Closes #92

Author: greenkeeper[bot]

package.json

@@ -60,7 +60,7 @@
     "chai-bignumber": "^3.0.0",
     "conventional-github-releaser": "^3.1.2",
     "coveralls": "^3.0.2",
-    "eslint": "^5.7.0",
+    "eslint": "^6.2.0",
     "eslint-config-airbnb": "^17.1.0",
     "eslint-config-airbnb-base": "^13.1.0",
     "eslint-config-standard": "^12.0.0",