Bump eslint from 6.8.0 to 7.18.0

Bumps [eslint](https://github.com/eslint/eslint) from 6.8.0 to 7.18.0.
- [Release notes](https://github.com/eslint/eslint/releases)
- [Changelog](https://github.com/eslint/eslint/blob/master/CHANGELOG.md)
- [Commits](eslint/eslint@v6.8.0...v7.18.0)

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

package.json

@@ -34,7 +34,7 @@
   "devDependencies": {
     "chai": "^4.2.0",
     "cheerio": "^1.0.0-rc.3",
-    "eslint": "^6.8.0",
+    "eslint": "^7.18.0",
     "eslint-config-hexo": "^4.1.0",
     "hexo": "^3.9.0",
     "mocha": "^6.2.2",