Bump lz4-sys from 1.9.2 to 1.9.4 (#1588)

* Bump lz4-sys from 1.9.2 to 1.9.4

Bumps [lz4-sys](https://github.com/10xGenomics/lz4-rs) from 1.9.2 to 1.9.4.
- [Release notes](https://github.com/10xGenomics/lz4-rs/releases)
- [Changelog](https://github.com/10XGenomics/lz4-rs/blob/master/CHANGELOG.md)
- [Commits](https://github.com/10xGenomics/lz4-rs/commits)

---
updated-dependencies:
- dependency-name: lz4-sys
  dependency-type: indirect
...

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

* bump lz4 to match lz4-sys

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Sebastian Kunert <skunert49@gmail.com>