pypy-3.8 flaky tests

[aiven-sal]

Tests run against pypy-3-8 randomly fail because of a segfault in the interpreter

e.g.

https://github.com/valkey-io/valkey-py/actions/runs/9284608789/job/25547347087#step:4:213

We should investigate.

[aiven-sal]

I believe I figured out what is going on here.
There are some bugs in Pypy 7.3.11's GC, the fix should be pypy/pypy#4928 which is part of 7.3.12
Unfortunately Pypy dropped 3.8 support in 7.3.12 (one year ago) and we will never get that fix.
I think we should just stop run tests against Pypy 3.8 and deprecate it.

[aiven-sal]

This is an interesting write up of the issue https://www.pypy.org/posts/2024/03/fixing-bug-incremental-gc.html
If anyone is curious.