chore(deps): bump fastify from 4.23.2 to 5.7.3 in /backup-server

Bumps [fastify](https://github.com/fastify/fastify) from 4.23.2 to 5.7.3.
- [Release notes](https://github.com/fastify/fastify/releases)
- [Commits](fastify/fastify@v4.23.2...v5.7.3)

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

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

Author: dependabot[bot]