chore(deps-dev): bump eslint from 3.19.0 to 6.6.0 (#209)

Bumps [eslint](https://github.com/eslint/eslint) from 3.19.0 to 6.6.0.
- [Release notes](https://github.com/eslint/eslint/releases)
- [Changelog](https://github.com/eslint/eslint/blob/master/CHANGELOG.md)
- [Commits](https://github.com/eslint/eslint/compare/v3.19.0...v6.6.0)

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

package.json

@@ -27,7 +27,7 @@
     "chai": "^3.5.0",
     "chromedriver": "^78.0.1",
     "cross-env": "^5.2.0",
-    "eslint": "^3.9.1",
+    "eslint": "^6.6.0",
     "finalhandler": "^1.1.0",
     "geckodriver": "^1.11.2",
     "global-replaceify": "^1.0.0",