Bump serve-static and express

Bumps [serve-static](https://github.com/expressjs/serve-static) to 1.16.2 and updates ancestor dependency [express](https://github.com/expressjs/express). These dependencies need to be updated together.


Updates `serve-static` from 1.15.0 to 1.16.2
- [Release notes](https://github.com/expressjs/serve-static/releases)
- [Changelog](https://github.com/expressjs/serve-static/blob/v1.16.2/HISTORY.md)
- [Commits](https://github.com/expressjs/serve-static/compare/v1.15.0...v1.16.2)

Updates `express` from 4.19.2 to 4.21.1
- [Release notes](https://github.com/expressjs/express/releases)
- [Changelog](https://github.com/expressjs/express/blob/4.21.1/History.md)
- [Commits](https://github.com/expressjs/express/compare/4.19.2...4.21.1)

---
updated-dependencies:
- dependency-name: serve-static
  dependency-type: indirect
- dependency-name: express
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

package.json

@@ -17,7 +17,7 @@
     "discord-api-types": "^0.37.2",
     "discord.js": "^14.0.0",
     "dotenv": "^16.0.0",
-    "express": "^4.19.2",
+    "express": "^4.21.1",
     "mysql2": "^2.3.3",
     "nanoid": "^3.0.0",
     "nodemon": "^2.0.15",