refactor: replace print() with logging in YouTubeConverter

[ahmedezzat2018]

Problem: YouTubeConverter used print() for error messages instead of
the standard logging module, bypassing the app's logging configuration.

Solution: Added import logging and a module-level logger, then replaced
all print() calls with logger.warning().

[VANDRANKI]

Clean refactor - using the module logger instead of print() is the right pattern for library code. Callers can configure the markitdown.converters._youtube_converter logger to control verbosity.

One nit: there is trailing whitespace on the logger = logging.getLogger(__name__) line. Not functional but will likely fail linting.

[ahmedezzat2018]

@microsoft-github-policy-service agree

[ahmedezzat2018]

Thanks for the feedback! I've removed the trailing whitespaceand reformatted the code using black. Looking forward to your thoughts

[VANDRANKI]

Trailing whitespace gone and black formatting applied consistently. All three print() calls correctly replaced with logger.warning(). LGTM.