graphics/py-pillow: Update to 7.0.0

• Repo-Copy the Pillow 6.2.2 release to graphics/py-pillow6 to retain backwards compatibility for Python 2 consumers as the Pillow 7.0.0 release dropped the support for Python 2.

• Apply conditional statements to use either Pillow 7.x or Pillow 6.x for consumers that can be built for Python 2 or newer.

• Exceptions are ports that can be built only for either Python 2 or Python 3. For the first case, consumers are just assigned to the repo-copied graphics/py-pillow6.

• Also remove Pillow from BUILD_DEPENDS of math/py-PyWavelets as it is not listed in setup.py as a build dependency [1] and relax the version requirements of Pillow for www/py-wagtail.

Release Notes:

• https://pillow.readthedocs.io/en/latest/releasenotes/index.html

Backward Incompatible Changes (7.0.0):

• https://pillow.readthedocs.io/en/latest/releasenotes/7.0.0.html#backwards-incompatible-changes

Detailed Changelog:

• https://github.com/python-pillow/Pillow/blob/7.0.0/CHANGES.rst

PR: 243665
Submitted by: sunpoet (patch for 7.0.0 and repo-copied version)
Reviewed by: koobs [1], sunpoet
Approved by: koobs (maintainer)
Differential Revision: https://reviews.freebsd.org/D23713