chore(deps): bump fastify in /examples/custom-receiver

Bumps [fastify](https://github.com/fastify/fastify) from 5.7.1 to 5.7.2.
- [Release notes](https://github.com/fastify/fastify/releases)
- [Commits](fastify/fastify@v5.7.1...v5.7.2)

---
updated-dependencies:
- dependency-name: fastify
  dependency-version: 5.7.2
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]