Bump hashbrown from 0.15.0 to 0.15.2 in /pixie-server

Bumps [hashbrown](https://github.com/rust-lang/hashbrown) from 0.15.0 to 0.15.2.
- [Changelog](https://github.com/rust-lang/hashbrown/blob/master/CHANGELOG.md)
- [Commits](https://github.com/rust-lang/hashbrown/commits)

---
updated-dependencies:
- dependency-name: hashbrown
  dependency-type: indirect
...

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