lang/rustpython: Fix build with rust 1.76.0

Import upstream patch [1] to fix the following error:
error[E0512]: cannot transmute between types of different sizes, or dependently-sized types

--> /wrkdirs/usr/ports/lang/rustpython/work/Parser-0.3.0/ast/src/impls.rs:60:1

[1] https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=270383

PR: 276920
Approved by: portmgr (build fix blanket)