Possible deadlock when running Python 3.11+ tests

[icemac]

Running the tests for Python 3.11 and 3.12 on GHA is currently cancelled after six hours of runtime.
Maybe we have (again) a deadlock here.

Example runs:

• Python 3.11: https://github.com/zopefoundation/zope.sqlalchemy/actions/runs/10870806212/job/30163863945
• Python 3.12: https://github.com/zopefoundation/zope.sqlalchemy/actions/runs/9986832358/job/27623911631?pr=83

[icemac]

Solved in #85 by not allowing the versions which run into a deadlock.
This might need some further investigation to find out which changes led to the deadlock and whether we might have to change something on our side.