- Don't use %python3_only command, but properly use alternatives.

- version update to 3.0.0
* #10: strftime now reverts to the stdlib behavior for %u.

- Drop py2 only dependency

- version update to 2.1.0
v2.1.0
======
- #9: Fixed error when date object is passed to ``strftime``.
- #11: ``strftime`` now honors upstream expectation of
rendering date values on time objects and vice versa.
- #10: ``strftime`` now honors ``%µ`` for rendering just
the "microseconds" as ``%u`` supported previously.
In a future, backward-incompatible release, the
``%u`` behavior will revert to the behavior as found
in stdlib.
v2.0.0
======
* Require Python 3.6 or later.
* Removed DatetimeConstructor.