cargo.eclass now supports `@` as a delimiter between package name and version as it's faster to parse and is already common in Rust world. Also, `${CARGO_CRATE_URIS}` should be used in SRC_URI instead now. References: * https://marc.info/?l=gentoo-dev&m=168718685909185&w=2 * https://marc.info/?l=gentoo-dev&m=167597571925550&w=2 * https://marc.info/?l=gentoo-dev&m=168694323423232&w=2