Bump polars from 0.19.7 to 0.19.8

Bumps [polars](https://github.com/pola-rs/polars) from 0.19.7 to 0.19.8.
- [Release notes](https://github.com/pola-rs/polars/releases)
- [Commits](pola-rs/polars@py-0.19.7...py-0.19.8)

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

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