Update rstest requirement from 0.19.0 to 0.21.0

Updates the requirements on [rstest](https://github.com/la10736/rstest) to permit the latest version.
- [Release notes](https://github.com/la10736/rstest/releases)
- [Changelog](https://github.com/la10736/rstest/blob/master/CHANGELOG.md)
- [Commits](la10736/rstest@v0.19.0...v0.21.0)

---
updated-dependencies:
- dependency-name: rstest
  dependency-type: direct:production
...

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

Cargo.toml

@@ -79,7 +79,7 @@ snafu = { version = "0.8.0", features = ["backtrace"] }
 
 [dev-dependencies]
 polars = { version = "0.40.0", features = ["parquet"] }
-rstest = "0.19.0"
+rstest = "0.21.0"
 pretty_env_logger = "0.5"
 
 [build-dependencies]