scanpypi: add support for the new PyPI infrastructure

scanpypi: add support for the new PyPI infrastructure

https://pypi.python.org URL has been changed to https://pypi.org.

Package's JSON object now contains sha256 checksum, so use it
instead of locally computed one. Change comments in the hash
file accordingly.

Signed-off-by: Yegor Yefremov <yegorslists@googlemail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
(cherry picked from commit 6766ff9d12c628332170098de9cff42625a2d0a3)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>