Bug#972246: numba ftbfs in unstable with python3.9 as supported python3 version

[Drew Parsons]

Source: numba
Followup-For: Bug #972246
X-Debbugs-Cc: Andreas Tille <andreas at fam-tille.de>

Hi Andreas, check the upstream bug.  The fix was merged only 4 days
ago, 0.52.0 does not have it.

We could try backporting PR#6579 to 0.52.0. Maybe it will work but
there is a reasonable chance that it won't.