package/python-pillow: bump to version 7.0.0

This patch bump Pillow to version 7.0.0.
Latest Pillow version doesn't support python2 anymore, thus
enforce the dependency on python3.

It updates also the LICENSE hash due to copyright year update.

Signed-off-by: Angelo Compagnucci <angelo@amarulasolutions.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>