fix: package.json & yarn.lock to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-HIGHLIGHTJS-1048676
- https://snyk.io/vuln/SNYK-JS-MARKED-174116
- https://snyk.io/vuln/SNYK-JS-MARKED-2342073
- https://snyk.io/vuln/SNYK-JS-MARKED-2342082
- https://snyk.io/vuln/SNYK-JS-MARKED-451540
- https://snyk.io/vuln/SNYK-JS-MARKED-584281
- https://snyk.io/vuln/SNYK-JS-STRIPTAGS-1312310

Author: snyk-bot

package.json

@@ -22,7 +22,7 @@
     "hexo-generator-index": "^2.0.0",
     "hexo-generator-tag": "^1.0.0",
     "hexo-renderer-ejs": "^2.0.0",
-    "hexo-renderer-marked": "^0.3.2",
+    "hexo-renderer-marked": "^5.0.0",
     "hexo-renderer-stylus": "^2.1.0",
     "hexo-server": "^3.0.0",
     "hoek": "^6.1.2",