fix: upgrade next from 12.3.1 to 12.3.4

Snyk has created this PR to upgrade next from 12.3.1 to 12.3.4.

See this package in npm:
https://www.npmjs.com/package/next

See this project in Snyk:
https://app.snyk.io/org/maidul98/project/53d4ecb6-6cc1-4918-aa73-bf9cae4ffd13?utm_source=github&utm_medium=referral&page=upgrade-pr

frontend/package.json

@@ -31,7 +31,7 @@
     "jspdf": "^2.5.1",
     "jsrp": "^0.2.4",
     "markdown-it": "^13.0.1",
-    "next": "^12.2.5",
+    "next": "^12.3.4",
     "posthog-js": "^1.34.0",
     "query-string": "^7.1.3",
     "react": "^17.0.2",