fix(neuralynx): handle unclosed files with unparseable TimeClosed

[Yi-111-a]

Fixes #1901

Summary

When reading Neuralynx files that were not properly closed (such as following an acquisition crash or interruption), the header line -TimeClosed File was not properly closed is matched by _closeDatetime2_pat = re.compile(r'-TimeClosed (?P<date>\S+) (?P<time>\S+)') with date='File' and time='was', raising dateutil.parser.ParserError: Unknown string format: File was.

Solution

• Wrap dateutil.parser.parse() in a try...except (ValueError, dateutil.parser.ParserError): pass block in _setTimeDate.
• If parsing fails, recording_closed remains unset (hdr.get('recording_closed') returns None, consistent with datasets lacking close time), while hdr['TimeClosed'] preserves the raw string 'File was not properly closed'.
• Added unit test test_unclosed_file_datetime in test_neuralynxrawio.py verifying header parsing.

Fixes #1901