Just testing what fields in a `Cargo.toml` can be updated after a crate has
been uploaded.

The Rust book touches on this but doesn't go in too deeply about specifics.

- `name`: Probably not?
- `version`: **Yes**, obviously
- `authors`: **No**, according to Rust book
- `edition`: ?
- `rust-version`: ?
- `description`: ?
- `documentation`: ?
- `readme`: ?
- `homepage`: ?
- `repository`: ?
- `license`/`license-file`: ?
- `keywords`: ?
- `categories`: Probably not?