Support pre-release versions

[DmitrySamoylov]

Hey! It looks like the following use case is not supported yet.

Let's say I have such versions in s3 bucket:

• 0.1.1
• 0.1.2-beta

And in Cargo.toml I have version = "0.1.2-beta". When trying to perform self-update, I get roughly this output in stdout:

New release found! v0.1.2-beta --> v0.1.2
New release is *NOT* compatible

mybin release status:
  * Current exe: "/usr/bin/mybin"
  * New exe release: "mybin-0.1.2-beta-x86_64-unknown-linux-gnu"
  * New exe download url: "https://<s3>/mybin-0.1.2-beta-x86_64-unknown-linux-gnu"

But expected behaviour is that self_update understands that binary is already up-to-date. Notice this line:

New release found! v0.1.2-beta --> v0.1.2

Obviously it counts mybin-0.1.2-beta-x86_64-unknown-linux-gnu as v0.1.2 and not as v0.1.2-beta. Probably the issue here is that it is hard to tell when pre-release version ends and when triple starts.

Pre-release versions definition: https://semver.org/#spec-item-9