python-compat: adapt to Python 3.11 BC breakage with `random.sample`
As per https://docs.python.org/3/whatsnew/3.11.html#porting-to-python-3-11:
"The population parameter of random.sample()
must be a sequence, and
automatic conversion of sets to lists is no longer supported.
Also, if the sample size is larger than the population size,
a ValueError
is raised"