adjust log stacklevel for py3.11.0b1; enable greenlet

adjust log stacklevel for py3.11.0b1; enable greenlet

Fixed issue where support for logging "stacklevel" implemented in
:ticket:`7612` required adjustment to work with recently released Python
3.11.0b1, also repairs the unit tests which tested this feature.

Install greenlet from a py311 compat patch.

re: the stacklevel thing, this is going to be very inconvenient
if we have to keep hardcoding numbers everywhere for every
new python version

Change-Id: I0c8f7293e98c0ca5cc544538284bfd1d3020cb1f
References: https://github.com/python-greenlet/greenlet/issues/288
Fixes: #8019