Cap setuptools version due to issues in the latest one.

Author: domdfcoding

.github/workflows/conda_ci.yml

@@ -37,7 +37,7 @@ jobs:
           python -VV
           python -m site
           python -m pip install --upgrade pip setuptools wheel
-          python -m pip install --upgrade "whey-conda" "setuptools>=40.6.0" "wheel>=0.34.2"
+          python -m pip install --upgrade "whey-conda" "setuptools<61,>=40.6.0" "wheel>=0.34.2"
           # $CONDA is an environment variable pointing to the root of the miniconda directory
           $CONDA/bin/conda config --add channels conda-forge
           $CONDA/bin/conda config --add channels domdfcoding

pyproject.toml

@@ -1,5 +1,5 @@
 [build-system]
-requires = [ "setuptools>=40.6.0", "wheel>=0.34.2",]
+requires = [ "setuptools<61,>=40.6.0", "wheel>=0.34.2",]
 build-backend = "setuptools.build_meta"
 
 [project]