pidgin/pidgin

Update our mozilla.pem file and document how to do so.
release-2.x.y
2021-06-03, Gary Kramlich
d235516f2d9c
Update our mozilla.pem file and document how to do so.

Also update mk-ca-bundle.pl as the version we had was very old.

Testing Done:
Verified bundles updated and clean works.

Bugs closed: PIDGIN-17535

Reviewed at https://reviews.imfreedom.org/r/722/
For information on writing a plugin for Purple, Pidgin or Finch, go
http://developer.pidgin.im and click on API. From there, see the
HOWTOs in the "Related Pages" section.
You can also generate this documentation locally by installing
doxygen and graphviz dot, then running "make docs" in the
source tree. The documentation will be in the docs/html directory.