Improve message when updater receipt is for a different uv executable (#9487)
Attempts to improve confusing messaging in cases like
https://github.com/astral-sh/uv/issues/6774#issuecomment-2504950681,
when the receipt is for a different uv executable.
```
❯ cargo run --all-features -q -- self update
warning: Self-update is only available for uv binaries installed via the standalone installation scripts.
The current executable is at `/Users/zb/workspace/uv/target/debug/uv` but the standalone installer was used to install uv to `/Users/zb/.cargo`. Are multiple copies of uv installed?
```
Requires https://github.com/axodotdev/axoupdater/pull/221
Closes https://github.com/astral-sh/uv/issues/6774