Bump express from 5.1.0 to 5.2.1 in /test/mcp (#280440)

Bumps [express](https://github.com/expressjs/express) from 5.1.0 to 5.2.1.
- [Release notes](https://github.com/expressjs/express/releases)
- [Changelog](https://github.com/expressjs/express/blob/master/History.md)
- [Commits](https://github.com/expressjs/express/compare/v5.1.0...v5.2.1)

---
updated-dependencies:
- dependency-name: express
  dependency-version: 5.2.1
  dependency-type: direct:production
...

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test/mcp/package.json

@@ -15,7 +15,7 @@
     "@modelcontextprotocol/sdk": "1.24.0",
     "@playwright/mcp": "^0.0.37",
     "cors": "^2.8.5",
-    "express": "^5.1.0",
+    "express": "^5.2.1",
     "minimist": "^1.2.8",
     "ncp": "^2.0.0",
     "node-fetch": "^2.6.7"