Add regex check for semver formatting in versioned python objects

[ahouseholder]

See https://semver.org/#is-there-a-suggested-regular-expression-regex-to-check-a-semver-string
...which describes:

^(?P<major>0|[1-9]\d*)\.(?P<minor>0|[1-9]\d*)\.(?P<patch>0|[1-9]\d*)(?:-(?P<prerelease>(?:0|[1-9]\d*|\d*[a-zA-Z-][0-9a-zA-Z-]*)(?:\.(?:0|[1-9]\d*|\d*[a-zA-Z-][0-9a-zA-Z-]*))*))?(?:\+(?P<buildmetadata>[0-9a-zA-Z-]+(?:\.[0-9a-zA-Z-]+)*))?$

We should implement a check at the init time of ssvc._mixins._Versioned that verifies this regex and throws an error if it is not matched.

Explainer: https://regex101.com/r/Ly7O1x/3/

[ahouseholder]

Question for @sei-vsarvepalli : Can we do something similar with json schema? If so, we should do a separate issue for that.

[sei-vsarvepalli]

yeh - sure. The only thing I can think of a while ago we were debating calver - if we are settled on semver, we should do it.

[sei-renae]

Is this Issue referring to python objects in /src/decision_points/, or is it obsolete because SSVC is using calver instead of semver? Thanks in advance for the clarification.

[ahouseholder]

It's not obsolete. We use calver for the overall project, but individual objects like decision points and decision point groups use semver. With the switch over to pydantic data classes in #674, this kind of data validation got a lot easier. I will have a PR in to resolve this issue shortly.