[target.x86_64-unknown-linux-gnu]
linker = "/usr/bin/clang-15"`
rustflags = ["-C", "link-arg=--ld-path=/usr/local/bin/mold"]

Can you put something like mold or env mold for better portability?

If not, I guess it's not so bad to edit and do git update-index --assume-unchanged .cargo/config.toml but it's a bit hacky since any further changes also get ignored.