build(deps-dev): bump fastify from 5.6.2 to 5.7.3

Bumps [fastify](https://github.com/fastify/fastify) from 5.6.2 to 5.7.3.
- [Release notes](https://github.com/fastify/fastify/releases)
- [Commits](https://github.com/fastify/fastify/compare/v5.6.2...v5.7.3)

---
updated-dependencies:
- dependency-name: fastify
  dependency-version: 5.7.3
  dependency-type: direct:development
...

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