pin setuptools<82 in bayes extra

setuptools 82 removed pkg_resources entirely, which httpstan still
imports at runtime; CI's prior `pip install --upgrade setuptools`
step grabs the latest, so an unpinned setuptools didn't help.

setup.py

@@ -130,7 +130,7 @@ setup(
     # Similar to `install_requires` above, these must be valid existing
     # projects.
     extras_require={  # Optional
-       'bayes': ['jax', 'jaxlib', 'numpyro', 'pystan', 'setuptools'],
+       'bayes': ['jax', 'jaxlib', 'numpyro', 'pystan', 'setuptools<82'],
        'neural': ['torch'],
        'tests': ['certifi'],
        'docs' : ['sphinx-rtd-theme', 'myst-parser'],