fix: upgrade Next.js to 15.5.10 to fix DoS vulnerability (#1820)

Author: Warren-Pitterson

application/CohortManager/src/Web/package-lock.json

@@ -17,7 +17,7 @@
   "dependencies": {
     "axe-playwright": "^2.1.0",
     "jwt-decode": "^4.0.0",
-    "next": "^15.5.9",
+    "next": "^15.5.10",
     "next-auth": "^5.0.0-beta.30",
     "nhsuk-frontend": "^10.0.0-internal.0",
     "react": "19.1.0",