fix(deps): update dependency prismjs to v1.21.0 [security]

Author: renovate-bot

package.json

@@ -46,7 +46,7 @@
     "@types/prismjs": "1.16.0",
     "@babel/runtime": "7.9.2",
     "classnames": "2.2.6",
-    "prismjs": "1.20.0",
+    "prismjs": "1.21.0",
     "react-markdown": "4.3.1"
   },
   "devDependencies": {