Provide easy access to version info.

[fermezz]

I understand setuptools_scm provides programmatic access to version info, but I think it would be nice if we could provide easy access in here, kinda following what pytest is doing. I can work on a PR, although if this is not something we'd want to do, let me know!

[blueyed]

Just out of interest: what's your use case?

[fermezz]

I have a few projects still running old versions of Django which latest pytest-django doesn't really support, so they don't have access to newer features. The idea is to port the implementation into those projects only when running pytest-django with a version lower than <some-version-of-pytest-django> so that once we can get them updated, those feature-ports are easily identifiable and removable. At the moment there's no easy way to do that. We could work around it by checking the Django version but other variables might come into play so I'm not sure that's optimal.

Does that make sense?