"Could not find requested crate" unless I revert to the git index

I attempted to begin a review:

```
$ cargo crev open embedded-sprites -uv 0.1.2
Updating crates.io index
Could not find requested crate. Try updating cargo's registry index cache?
```

On a suspicion that the problem has to do with Cargo's new sparse index protocol, I tried:

```
$ CARGO_REGISTRIES_CRATES_IO_PROTOCOL=git cargo crev open embedded-sprites -uv 0.1.2
```

and it succeeded. So, it seems that `cargo-crev` is making some assumption that depends on the old protocol.

* Version: 0.24.3
* How did you install `crev`: `cargo install`
* What OS/platform: macOS 12.6.8

Start by reproducing `cargo crev open embedded-sprites -uv 0.1.2` with the default sparse protocol, then compare it with `CARGO_REGISTRIES_CRATES_IO_PROTOCOL=git`. Trace the crate lookup entry point and identify why the default protocol fails; done means the command finds the requested crate without forcing the git protocol.

Written by the indexing model from the issue text.