CI: pin setuptools on 1.1.x (pandas-dev#36048)

Author: simonjayhawkins

ci/setup_env.sh

@@ -148,7 +148,7 @@ python setup.py build_ext -q -i -j2
 # - py35_compat
 # - py36_32bit
 echo "[Updating pip]"
-python -m pip install --no-deps -U pip wheel setuptools
+python -m pip install --no-deps -U pip wheel "setuptools<50.0.0"
 
 echo "[Install pandas]"
 python -m pip install --no-build-isolation -e .