ruff: add worktree support to build.rs (#14896)
Without this, `cargo insta test` re-compiles every time it is run, even
if there are no changes. With this, I can re-run `cargo insta test` (or
other `cargo build` commands) without it resulting in re-compiles.
I made an identical change to uv a while back:
https://github.com/astral-sh/uv/pull/6825
