Fix npm audit findings in postcss and react-router

Bump postcss to 8.5.23 and react-router to 8.3.0 to clear their high-severity advisories. Leave nested brace-expansion issues for a follow-up that won't break older minimatch consumers.

Signed-off-by: Sacha Al Himdani <sacha@probo.com>

apps/compliance-portal/package.json

@@ -23,7 +23,7 @@
     "react-i18next": "^17.0.10",
     "react-pdf": "^10.3.0",
     "react-relay": "^21.0.1",
-    "react-router": "^8.1.0",
+    "react-router": "^8.3.0",
     "relay-runtime": "^21.0.1"
   },
   "devDependencies": {