chore(deps): bump fastify from 4.29.1 to 5.7.3 in /passkey-bundler

Bumps [fastify](https://github.com/fastify/fastify) from 4.29.1 to 5.7.3.
- [Release notes](https://github.com/fastify/fastify/releases)
- [Commits](fastify/fastify@v4.29.1...v5.7.3)

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

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Author: dependabot[bot]