Add categorical datatype

[mathisdrn]

dataframely doesn't appear to support pl.categorical datatype. Could this be added ?

[borchero]

Due to the StringCache, support for categoricals in dataframely would have always been a little odd. However, polars recently removed the StringCache entirely (see pola-rs/polars#23016). Once that change is released (next week or the week after according to the polars Discord), we should add the Categorical type here as well :) until then, Enum might fit your use case as well?

[mathisdrn]

until then, Enum might fit your use case as well?

I am using Categorical instead of Enum because it's easier to work with than Enum. Also plotting library provides better default when a column is Categorical instead of String or Int. I am unsure whether this also applies to Enum.
I will probably to resort to a final cast to Categorical after using validate.