ieeg_filtered_speech incorrect type for notch column values.

[rwblair]

https://github.com/bids-standard/bids-examples/blob/c557d1f33a8168c21126419f7033f8aa9c809e0c/ieeg_filtered_speech/sub-ir05/ieeg/sub-ir05_task-FilteredSpeech_channels.tsv

https://bids-specification.readthedocs.io/en/stable/04-modality-specific-files/04-intracranial-electroencephalography.html#channels-description-_channelstsv

Should array values for notch be accepted?

[effigies]

Note that the array values were present before we ever tried to schematize. It is not specified in the text, but I would take examples from the BEP leads as authoritative here and say we should update the schema. Which I guess means that they're strings that need parsing.