[express] Add express@5 to peerDependencies

`express@5` is out, and is mostly compatible with `express@4` (see [the migration guide](https://expressjs.com/en/guide/migrating-5.html)). At least for React Router usage the differences should be immaterial.

This would allow users to integrate React Router into their existing `express@5` apps, or use `express@5` as a hosting server, without having to fiddle with `--legacy-peer-deps` or similar.

Author: rossipedia

packages/react-router-express/package.json

@@ -63,7 +63,7 @@
     "wireit": "0.14.9"
   },
   "peerDependencies": {
-    "express": "^4.17.1",
+    "express": "^4.17.1 || ^5",
     "react-router": "workspace:*",
     "typescript": "^5.1.0"
   },