Update eslint requirement from ^5.16.0 to ^6.1.0

Updates the requirements on [eslint](https://github.com/eslint/eslint) to permit the latest version.
- [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/v5.16.0...v6.1.0)

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

package.json

@@ -44,7 +44,7 @@
     "cross-env": "^5.2.0",
     "cssnano": "^4.1.10",
     "del": "^5.0.0",
-    "eslint": "^5.16.0",
+    "eslint": "^6.1.0",
     "eslint-config-prettier": "^6.0.0",
     "eslint-plugin-import": "^2.17.3",
     "glob": "^7.1.4",