trunk build failing

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It seems like pypy-3.9 and mypy have broken on trunk between commits, so some dependency has shifted in a way that breaks a bunch of Deferred tests (???).

See the build history here: https://github.com/twisted/twisted/actions/runs/7356600638

We really need to pin mor ethings.

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looks like the problem is that pyOpenSSL added some annotations, and pypy did … something … to stack introspection pypy/pypy#4850