feat: add deprecation warning for beacon translation

[korikuzma]

close #568

• One of the Beacon leads (@mbaudis) requested this to be removed since it does not follow the standard, for now we will add a deprecation message and remove this in v3.
• Added typing_extensions as an extras dep

[jsstevenson]

Strictly speaking, as a breaking change, is this a -> 3.0 release? (or can we 🙈 about it)

[korikuzma]

Strictly speaking, as a breaking change, is this a -> 3.0 release? (or can we 🙈 about it)

Yes 3.0 release

[ahwagner]

For those that don't want to do major version upgrades–perhaps a related PR that just adds a deprecation warning for the 2.x series? Just not sure when we want to pull the trigger on a major version release, and if there are other features we might want to merge in to something like that.

[korikuzma]

@ahwagner Deprecation warning makes sense. I don't think we have established release strategy / branch strategies for our reference implementations. I know we've had discussions, but I don't think it's been documented anywhere on what we chose. So we should probably have that discussion.

[jsstevenson]

Maybe we could merge an implementation of a deprecation warning now, and merge this PR into a 3.x branch? I think we'd want to assess whether there are other breaking changes we might want to include in a new major version release before we put one out

[korikuzma]

@ga4gh/vrs-python-maintainers This is ready for review now