py-uvloop: updated to 0.12.2

v0.12.2
Bug Fixes
* Fix circular references in SSL implementation to reduce
the need for GC.
* Fix a memory leak in call_later() and call_at().
  The leak occurred when a callback argument had a reference to
  the event loop.
* Fix compilation warnings.
* Round (instead of flooring) delay in call_later().
  This ensures that the callback is never called slightly before
  the specified time.

(adam)