BUG: bf28ddd BUG: functools.partial objects do not always have a __module__ attr in Python 3.9

Fixes #1232
Thanks #1249

Author: kernc

backtesting/lib.py

@@ -639,7 +639,7 @@ def optimize(self, **kwargs) -> pd.DataFrame:
 
 __all__ = [getattr(v, '__name__', k)
            for k, v in globals().items()                        # export
-           if ((callable(v) and v.__module__ == __name__ or     # callables from this module
+           if ((callable(v) and getattr(v, '__module__', None) == __name__ or  # callables from this module
                 k.isupper()) and                                # or CONSTANTS
                not getattr(v, '__name__', k).startswith('_'))]  # neither marked internal