Migrate arrow-pyarrow-testing to Rust 2024 (#8487)

# Which issue does this PR close?

- Contribute to #6827

# Rationale for this change

Splitting up #8227.

# What changes are included in this PR?

Migrate `arrow-pyarrow-testing` to Rust 2024

# Are these changes tested?

CI

# Are there any user-facing changes?

Yes

Author: mbrobbel

arrow-pyarrow-testing/Cargo.toml

@@ -39,7 +39,7 @@ repository = "https://github.com/apache/arrow-rs"
 authors = ["Apache Arrow <[email protected]>"]
 license = "Apache-2.0"
 keywords = ["arrow"]
-edition = "2021"
+edition = "2024"
 rust-version = "1.85"
 publish = false
 

arrow-pyarrow-testing/src/lib.rs

@@ -17,4 +17,4 @@
 
 //! This crate exists to provide a test environment for the `arrow-pyarrow` crate.
 //! It is not intended to be used by itself. See comments in Cargo.toml for more
-//! details.
+//! details.