[feat] Support Versioning for Hub Validators

[CalebCourier]

Description
Currently installing a hub validator always installs the latest assuming it is not already installed or cached on the users machine. We should enable versioning on hub validators so a user can install and lock to a specific verison.

Why is this needed
Authors need to be able to specify what types of changes are occurring via semver.
Users need to be able to update only when they're ready and lock when necessary.

Implementation details
Since hub installs already utilize git installations via pip, we just need to track valid versions in the manifest index and allow authors to specify versions via branches, commit hashes, or tags (preferred).

End result
A user can install a specific version via guardrails hub install hub://guardrails/competitor_check@1.2.3