build(deps): Bump spin from 0.9.3 to 0.9.4

Bumps [spin](https://github.com/mvdnes/spin-rs) from 0.9.3 to 0.9.4.
- [Release notes](https://github.com/mvdnes/spin-rs/releases)
- [Changelog](https://github.com/mvdnes/spin-rs/blob/master/CHANGELOG.md)
- [Commits](https://github.com/mvdnes/spin-rs/commits)

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

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