Bump eslint from 3.19.0 to 4.19.1

Bumps [eslint](https://github.com/eslint/eslint) from 3.19.0 to 4.19.1.
- [Release notes](https://github.com/eslint/eslint/releases)
- [Changelog](https://github.com/eslint/eslint/blob/master/CHANGELOG.md)
- [Commits](eslint/eslint@v3.19.0...v4.19.1)

Signed-off-by: dependabot[bot] <support@github.com>

package.json

@@ -6,7 +6,7 @@
   "main": "./lib/upn.js",
   "devDependencies": {
     "coveralls": "^2.13.1",
-    "eslint": "^3.19.0",
+    "eslint": "^4.19.1",
     "eslint-config-airbnb-base": "^11.1.3",
     "eslint-plugin-import": "^2.2.0",
     "mocha": "^3.4.1",