hxntools.__version__ is missing

[jklynch]

In [1]: import hxntools

In [2]: hxntools.__version__
---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
Cell In[2], line 1
----> 1 hxntools.__version__

AttributeError: module 'hxntools' has no attribute '__version__'

In [3]: import versioneer

In [4]: versioneer.get_version()
Out[4]: '0.6.0'

[mrakitin]

I think we need to have a non-empty __init__ file, such as in https://github.com/NSLS-II/scientific-python-cookiecutter/blob/main/%7B%7B%20cookiecutter.repo_name%20%7D%7D/%7B%7B%20cookiecutter.package_dir_name%20%7D%7D/__init__.py.