Log Message:
py-ipython: updated to 7.15.0

IPython 7.15 brings a number of bug fixes and user facing improvements.

Misc Noticeable changes:
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 - Long completion name have better elision in terminal
 - I've started to test on Python 3.9 and fix some errors.
 - Hi DPI scaling of figures when using qt eventloop
 - Document the ability to have systemwide configuration for IPython.
 - Fix issues with input autoformatting
 - ``IPython.core.debugger.Pdb`` is now interruptible
 - Video HTML attributes