Bump fastify from 5.8.2 to 5.8.4

Bumps [fastify](https://github.com/fastify/fastify) from 5.8.2 to 5.8.4.
- [Release notes](https://github.com/fastify/fastify/releases)
- [Commits](fastify/fastify@v5.8.2...v5.8.4)

---
updated-dependencies:
- dependency-name: fastify
  dependency-version: 5.8.4
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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Author: dependabot[bot]