sets lower bound for scantree (#30)

Add requires-python metadata (#28)

* Add requires-python metadata through the addition of setuptools's
  python_requires in setup.py.
   - c.f. https://peps.python.org/pep-0621/#requires-python

* The addition of requires-python is to provide guards to keep older
  CPython versions from installing releases that could contain
  unrunnable code.

Merge pull request #27 from andhus/formatting-follow-up

Formatting follow up

Merge pull request #24 from andhus/fix-versioneer

Re-inits `versioneer` and adds missing `cmdclass` to `setup.py`

Merge pull request #24 from andhus/fix-versioneer

Re-inits `versioneer` and adds missing `cmdclass` to `setup.py`

Merge pull request #23 from andhus/publish-workflow

[WIP] Auto publishing

bump version -> 0.2.1

Merge pull request #1 from andhus/dirhash_standard

Implementation based on the Dirhash Standard