Using python standard version names

[bknueven]

Fixes # .

Summary/Motivation:

This is what setuptools ends up calling this version anyways:

~/.local/lib/python3.7/site-packages/setuptools/dist.py:452: UserWarning: Normalizing '0.5.2-dev' to '0.5.2.dev0'

Changes proposed in this PR:

• Change version from 0.5.2-dev to 0.5.2.dev0.

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