fix: package.json to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-MARKED-1070800

Author: snyk-bot

package.json

@@ -28,7 +28,7 @@
     "js-cookie": "^2.2.1",
     "js-search": "^2.0.0",
     "lodash": "^4.17.21",
-    "marked": "^1.1.1",
+    "marked": "^2.0.0",
     "node-sass": "^4.14.1",
     "prism-react-renderer": "^1.2.0",
     "prop-types": "^15.7.2",