feat: support Vite v6 in mocker package

This avoids warnings like:

```
└─┬ vitest 3.0.0-beta.2
  └─┬ @vitest/mocker 3.0.0-beta.2
    └── ✕ unmet peer vite@^5.0.0: found 6.0.3
```

packages/mocker/package.json

@@ -55,7 +55,7 @@
   },
   "peerDependencies": {
     "msw": "^2.4.9",
-    "vite": "^5.0.0"
+    "vite": "^5.0.0 || ^6.0.0"
   },
   "peerDependenciesMeta": {
     "msw": {