Update polars requirement from 0.38.0 to 0.39.2

Updates the requirements on [polars](https://github.com/pola-rs/polars) to permit the latest version.
- [Release notes](https://github.com/pola-rs/polars/releases)
- [Commits](pola-rs/polars@rs-0.38.0...rs-0.39.2)

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

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

Cargo.toml

@@ -78,7 +78,7 @@ pythonize = { version = "0.20", optional = true }
 snafu = { version = "0.8.0", features = ["backtrace"] }
 
 [dev-dependencies]
-polars = { version = "0.38.0", features = ["parquet"] }
+polars = { version = "0.39.2", features = ["parquet"] }
 rstest = "0.18.1"
 pretty_env_logger = "0.5"