add version string

[bpinsard]

What would you like to see added in this software?

I coded niworkflows/smriprep to report the gradunwarp version used, but it is missing in the current python package.
@effigies I think you have expertise in python packaging, in particular in versioneer setup if you think that's what we should use, and I could use your help with that.

Do you have any interest in helping implement the feature?

Yes, but I would need guidance

Additional information / screenshots

No response

[effigies]

gradunwarp currently has the version string in gradunwarp.core.globals.VERSION. You could just import that in __init__.py:

from .core.globals import VERSION as __version__

Then when it's time to release, you use bumpver as described in Washington-University#15 (comment).

All that said, we could switch to versioneer or setuptools_scm, if you prefer to just make tags.

[bpinsard]

first option is good for now, thanks!