shells/nu_plugin_polars: Fix build with rust 1.97.0

Import upstream commit [1] to fix the following error:

error[E0512]: cannot transmute between types of different sizes, or dependently-sized types

--> /wrkdirs/usr/ports/shells/nu_plugin_polars/work/nu_plugin_polars-0.114.0/cargo-crates/ethnum-1.5.2/src/error.rs:16:14
 |

16 | unsafe { mem::transmute(()) }

|              ^^^^^^^^^^^^^^
|
= note: source type: `()` (0 bits)
= note: target type: `TryFromIntError` (8 bits)

[1] https://github.com/nlordell/ethnum-rs/commit/87e3457c095c98fcac554548ee80f56e0cfb80ae

PR: 296645
Approved by: portmgr (build fix blanket)