Bump hexo from 3.9.0 to 4.2.0

Bumps [hexo](https://github.com/hexojs/hexo) from 3.9.0 to 4.2.0.
- [Release notes](https://github.com/hexojs/hexo/releases)
- [Commits](hexojs/hexo@3.9.0...4.2.0)

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

package.json

@@ -36,7 +36,7 @@
     "cheerio": "^1.0.0-rc.3",
     "eslint": "^6.8.0",
     "eslint-config-hexo": "^4.1.0",
-    "hexo": "^3.9.0",
+    "hexo": "^4.2.0",
     "mocha": "^6.2.2",
     "nyc": "^15.0.0"
   },