rust: support arrow 59

[lidavidm]

What feature or improvement would you like to see?

We will need to drop support for arrow <= 57, which came out ~8 months ago (vs ~2 years ago for 53):

error[E0599]: no function or associated item named `new` found for struct `UnionFields` in the current scope
   --> /home/lidavidm/Code/arrow-adbc/rust/core/src/schemas.rs:37:22
    |
 37 |         UnionFields::new(
    |                      ^^^ function or associated item not found in `UnionFields`
    |
note: if you're trying to build a new `UnionFields` consider using one of the following associated functions:
      UnionFields::empty
      UnionFields::try_new
      UnionFields::from_fields
      UnionFields::try_from_fields

[lidavidm]

We could add a feature to keep supporting older arrow crates, perhaps?

[eitsupi]

Can we merge #4043? 🤔

[lidavidm]

Ah, thanks for the reminder. Since nobody objected I'll see about fixing up and merging the PR