chore(package): update eslint to version 6.8.0

Closes #59

Author: greenkeeper[bot]

package.json

@@ -48,7 +48,7 @@
     "babel-preset-es2017": "^6.24.1",
     "babel-preset-stage-0": "^6.24.1",
     "codecov": "^3.0.0",
-    "eslint": "^4.12.0",
+    "eslint": "^6.8.0",
     "eslint-config-airbnb-base": "^12.1.0",
     "eslint-plugin-import": "^2.8.0",
     "husky": "^1.0.0",