Fix for polars 1.33.0 (dtype becoming mandatory)

[charles-turner-1]

Change Summary

• Specifies that iterable columns are decoded to the polars dtype pl.List[pl.Utf8] when opening catalogs with polars. (see https://docs.pola.rs/api/python/dev/reference/expressions/api/polars.Expr.str.json_decode.html)
• Update the ci/environment.yml to use polars>=1.33.0

Related issue number

N/A

Checklist

• [x] Unit tests for the changes exist
• [x] Tests pass on CI
• [x] Documentation reflects the changes where applicable