changed default of None to 1

if the min_num_stft_windows is set to None the the value become 0, and therefore logic allows for 0 windows per decimation level which raises an error.  Set default to 1, which eliminates 0 windows.

Author: kujaku11

aurora/pipelines/transfer_function_kernel.py

@@ -316,7 +316,7 @@ def update_processing_summary(self):
             raise ValueError(msg)
 
     def validate_decimation_scheme_and_dataset_compatability(
-        self, min_num_stft_windows=None
+        self, min_num_stft_windows=1
     ):
         """
         Checks that the decimation_scheme and dataset are compatable.