Python 3.11 support

[drws]

Python 3.11 is being rolled out nowadays and unfortunately it introduces some changes that break Friture build. gcc exits with code 1 and:

friture_extensions/exp_smoothing_conv.c:198:12: fatal error: longintrepr.h: No such file or directory

It seems to be widely known issue with 3.10 -> 3.11 migration: link1, link2, link3, link4, ...