routes/crate/version: Simplify serialize() method
routes/crate/version: Simplify serialize() method

Susurrus/crates.io,rust-lang/crates.io,achanda/crates.io,rust-lang/crates.io,achanda/crates.io,steveklabnik/crates.io,steveklabnik/crates.io,Susurrus/crates.io,steveklabnik/crates.io,Susurrus/crates.io,achanda/crates.io,Susurrus/crates.io,rust-lang/crates.io,achanda/crates.io,rust-lang/crates.io,steveklabnik/crates.io