primitive-types: add repository URL to Cargo.toml (#844)

This adds the repository URL to the Cargo manifest of `primitive-types`,
so that the crate published on crates.io can be automatically linked
back to the source repository.

primitive-types/Cargo.toml

@@ -4,6 +4,7 @@ version = "0.12.2"
 authors = ["Parity Technologies <admin@parity.io>"]
 license = "MIT OR Apache-2.0"
 homepage = "https://github.com/paritytech/parity-common"
+repository = "https://github.com/paritytech/parity-common"
 description = "Primitive types shared by Ethereum and Substrate"
 edition = "2021"
 rust-version = "1.60.0"