Pin setuptools to < 6

New versions have limited support for setup.py

Author: ppolewicz

setup.py

@@ -109,7 +109,7 @@ def read_requirements(extra=None):
     # for example:
     # $ pip install -e .[dev,test]
     extras_require={'doc': read_requirements('doc')},
-    setup_requires=['setuptools_scm'],
+    setup_requires=['setuptools_scm<6.0'],
     use_scm_version=True,
 
     # If there are data files included in your packages that need to be