chore: Remove dead code

No need to pass pages-router specific code here,
as this branch now only runs in the app router context.

packages/nuqs/src/update-queue.ts

@@ -198,9 +198,7 @@ function flushUpdateQueue(router: Router): [URLSearchParams, null | unknown] {
           // Call the Next.js router to perform a network request
           // and re-render server components.
           router.replace(url, {
-            scroll: false,
-            // @ts-expect-error - pages router fix, but not exposed in navigation types
-            shallow: false
+            scroll: false
           })
         })
       }