CLN: Drop compatiblity line from versioneer

We can safely assume this file is going to
be (or should be) compatible with whatever
Python versions pandas itself supports.

Author: gfyoung

versioneer.py

@@ -8,7 +8,6 @@
 * https://github.com/warner/python-versioneer
 * Brian Warner
 * License: Public Domain
-* Compatible With: python3.5+, and pypy
 * [![Latest Version]
 (https://pypip.in/version/versioneer/badge.svg?style=flat)
 ](https://pypi.org/project/versioneer/)