Pin types-setuptools to <67.4.0.3

The mypyc build is failing on `master` due to the latest release of `types-setuptools`: see, e.g. https://github.com/python/mypy/actions/runs/4275505309/jobs/7442902732.

python#14787 fixes the _build_ but there's still a bunch of mypyc tests failing on that PR. I haven't got time to debug them right now (and I'm not a mypyc expert, anyway!), so this is a stopgap PR to pin `types-setuptools` so that we avoid the latest release.

build-requirements.txt

@@ -1,5 +1,6 @@
 # NOTE: this needs to be kept in sync with the "requires" list in pyproject.toml
 -r mypy-requirements.txt
 types-psutil
-types-setuptools
+# TODO: fix build when using the latest version of types-setuptools
+types-setuptools<67.4.0.3
 types-typed-ast>=1.5.8,<1.6.0