cargo-c build failure - rust version?

[Greg Troxel <gdt%lexort.com@localhost>]

===> Creating toolchain wrappers for cargo-c-0.9.30
===> Configuring for cargo-c-0.9.30
=> Checking for portability problems in extracted files
===> Building for cargo-c-0.9.30
error: package `clap_derive v4.5.0` cannot be built because it requires rustc 1.74 or newer, while the currently active rustc version is 1.73.0
Either upgrade to rustc 1.74 or newer, or use
cargo update -p clap_derive@4.5.0 --precise ver
where `ver` is the latest version of `clap_derive` supporting rustc 1.73.0
*** Error code 101


But lang/rust-bin is at 1.73.0.