Bump eslint from 6.8.0 to 7.4.0

Bumps [eslint](https://github.com/eslint/eslint) from 6.8.0 to 7.4.0.
- [Release notes](https://github.com/eslint/eslint/releases)
- [Changelog](https://github.com/eslint/eslint/blob/master/CHANGELOG.md)
- [Commits](eslint/eslint@v6.8.0...v7.4.0)

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

package.json

@@ -30,7 +30,7 @@
   },
   "devDependencies": {
     "coveralls": "^3.0.4",
-    "eslint": "^6.1.0",
+    "eslint": "^7.4.0",
     "eslint-config-hexo": "^3.0.0",
     "mocha": "^6.1.4",
     "npm-run-all": "^4.1.5",