change versioning scheme of clippy_lints

[oli-obk]

As mentioned in rust-lang/rust#50767, updating the clippy submodule in the rustc repo can break rls and thus break nightlies.

Yesssss!, we can now ensure that all nightlies have a working clippy if we want to

No we are of course not doing this :P

Anyway. My suggestion is to change the versioning scheme of the clippy_lints crate. Instead of syncing with the clippy crate, we start producing 0.x.y versions, where x is updated when we change the API of clippy_lints (so when rustc forces us to change the API) and y is updated whenever we do a rustup.

This means there'll be a lot fewer version bumps to the clippy crate, as the clippy_lints crate in the background would automatically update via patch versions.

Is this suggestion abusing semver? Other ideas?