fix(cargo): prevent crate filename collision

[ThomasFrans]

cargo has a bug that prevents correct handling of similarly named crates in the same package. Rename the internal library crate to prevent error messages. rust-lang/cargo#10368

Describe your changes

Rename the library crate in the ncspot package. Instead of the implicit name ncspot, give it a name in the cargo manifest.

Checklist before requesting a review

• Documentation was updated (i.e. due to changes in keybindings, commands, etc.)
• Changelog was updated with relevant user-facing changes (eg. not dependency updates,
  not performance improvements, etc.)

[ThomasFrans]

This solves a minor issue when generating documentation for the binary crate. Without this fix, it throws a warning like in the following image.