chore(deps-dev): bump eslint from 3.19.0 to 6.7.2

Bumps [eslint](https://github.com/eslint/eslint) from 3.19.0 to 6.7.2.
- [Release notes](https://github.com/eslint/eslint/releases)
- [Changelog](https://github.com/eslint/eslint/blob/master/CHANGELOG.md)
- [Commits](eslint/eslint@v3.19.0...v6.7.2)

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

package.json

@@ -42,7 +42,7 @@
     "browserify": "^13.0.0",
     "buble": "^0.15.1",
     "coveralls": "^2.11.9",
-    "eslint": "^3.10.2",
+    "eslint": "^6.7.2",
     "minify": "^2.0.5",
     "mkdirp": "^0.5.1",
     "nodemon": "^1.11.0",