Situation

If you pass negative numbers into semver.VersionInfo it doesn't raise any errors:

>>> import semver
>>> semver.VersionInfo(-2)                                                                                                                           
VersionInfo(major=-2, minor=0, patch=0, prerelease=None, build=None)

Tested with latest 2.11.0

Proposal

I guess, this shouldn't happen. We should raise a ValueError exception.
Would integrate that into a 2.12.0 release and into the upcoming 3.0.0-alpha0.

@tlaferriere Thomas, can you conform? Do you agree?