Upgrade: Bump eslint from 2.13.1 to 6.6.0

Bumps [eslint](https://github.com/eslint/eslint) from 2.13.1 to 6.6.0.
- [Release notes](https://github.com/eslint/eslint/releases)
- [Changelog](https://github.com/eslint/eslint/blob/master/CHANGELOG.md)
- [Commits](eslint/eslint@v2.13.1...v6.6.0)

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

package.json

@@ -25,7 +25,7 @@
   },
   "dependencies": {},
   "devDependencies": {
-    "eslint": "^2.13.0",
+    "eslint": "^6.6.0",
     "eslint-config-gulp": "^3.0.1",
     "expect": "^1.20.2",
     "istanbul": "^0.4.3",