devel/dtool: Fix build with rust-1.76.0
Import upstream patch [1] to fix the following error:
error[E0310]: the parameter type T may not live long enough
--> /wrkdirs/usr/ports/devel/dtool/work/dtool-0.12.0/cargo-crates/rustc-serialize-0.3.24/src/serialize.rs:1155:5
PR: 276920
Approved by: portmgr (build fix blanket)