Update Cargo.toml: add license & crate_type Deprecation

[parsapoorsh]

+ license = "GPL-3.0-only"

- crate_type = ["cdylib"]
+ crate-type = ["cdylib"]

this fixes:

$ cargo deb
warning: `crate_type` is deprecated in favor of `crate-type` and will not work in the 2024 edition
warning: license field is missing in Cargo.toml