package/python-idna: bump to version 2.9

The license file hash has changed, due to the following changes:

 - A line "License: bsd-3-clause" is being added

 - The copyright year is updated to "Copyright (c) 2013-2020, Kim
   Davies. All rights reserved."

 - Details about portions of the codec and unit tests code being under
   the PSF license are removed.

 - Details about the unit tests including Unicode License Agreement
   code are removed.

Signed-off-by: James Hilliard <james.hilliard1@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>