Bump fastify from 3.21.6 to 3.29.4 in /example/fastify

Bumps [fastify](https://github.com/fastify/fastify) from 3.21.6 to 3.29.4.
- [Release notes](https://github.com/fastify/fastify/releases)
- [Commits](fastify/fastify@v3.21.6...v3.29.4)

---
updated-dependencies:
- dependency-name: fastify
  dependency-type: direct:production
...

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

example/fastify/package.json

@@ -8,7 +8,7 @@
     "start": "node index.js"
   },
   "dependencies": {
-    "fastify": "3.21.6",
+    "fastify": "3.29.4",
     "i18next": "21.1.1",
     "i18next-http-middleware": "3.1.4",
     "i18next-fs-backend": "1.1.1"