downloads.planetmirror.com and public.planetmirror.com force Temporary
Redirects unless you've visited both sites. They're designed for
interactive browser use, and there doesn't seem to be a reasonable
work-around.

python.planetmirror.com no longer mirrors python packages.

Therefore, remove all of the above.

PR: ports/112092
Submitted by: Marcin Simonides <marcin@studio4plus.com>