Update to version 0.20.2

This is my first submit request so sorry if I'm doing stuff wrong

I've been bitten by current Factory's okular stopping with Bogus memory
allocation size on certain PDFs, see
https://bugs.kde.org/show_bug.cgi?id=304051. This is actually a poppler bug,
see https://bugs.freedesktop.org/show_bug.cgi?id=49523, which is fixed in git
on the 0.20 branch but not available in a release yet. I expect 0.20.3 to be
out around August 10 and then I'll submit another update to that version. I
did this submission separately to try out the process and see how it goes.

There's an SO name bump unfortunately, I don't know if that means this update
can't go into 12.2. (forwarded request 129489 from cataliniacob)