Chore: Fix pandas testing dependency by downgrading to pandas 2.0

ImportError: cannot import name 'makeTimeDataFrame' from 'pandas._testing'

Author: amotl

setup.py

@@ -75,7 +75,7 @@ def read(path):
               'dask',
               'stopit>=1.1.2,<2',
               'flake8>=4,<7',
-              'pandas',
+              'pandas<2.1',
               'pytz',
               ],
         doc=['sphinx>=3.5,<8',