Add metadata for cargo-binstall

[orhun]

This PR updates the Cargo.toml of lychee to add cargo-binstall metadata as mentioned in #59 (comment)

Tested as follows:

$ cargo binstall lychee --manifest-path lychee-bin/Cargo.toml --dry-run

 INFO resolve: Resolving package: 'lychee'
 WARN The package lychee v0.13.0 will be downloaded from github.com
 INFO This will install the following binaries:
 INFO   - lychee (lychee -> /home/orhun/.cargo/bin/lychee)
 INFO Dry-run: Not proceeding to install fetched binaries
 INFO Done in 4.958623872s

[mre]

Awesome @orhun! Tested and works. ❤️