fix: catch OSError when exiftool binary is missing (#1960)

[doitgo]

Fixes #1960
When exiftool_path points to a binary that does not exist, the subprocess.run calls raised FileNotFoundError, which propagated unhandled through exiftool_metadata() and crashed the whole conversion.

Add OSError to the except clauses at both subprocess.run sites and wrap the error in a RuntimeError that includes the path, giving users a clear, actionable error message.

Add a regression test for the missing-binary case and a sanity check that the exiftool_path=None early return still works.

[doitgo]

Hi @afourney,

I'd like to draw your attention to PR #2082, which fixes #1960.

Issue: when the configured exiftool path points to a binary that doesn't exist, the current code raises an unhandled FileNotFoundError that crashes the entire conversion.

Fix (+27 / -2 across 2 files):

• src/markitdown/converters/_exiftool.py: catch OSError (parent of FileNotFoundError / PermissionError) at both subprocess.run sites and re-raise as RuntimeError with the offending path included for easier debugging.
• tests/test_exiftool_converter.py: add a regression test for the missing-binary case and a sanity check that the exiftool_path=None early-return path still returns {}.

Local tests pass. Could you or another maintainer take a look when you have a moment? Happy to adjust the implementation, the error message wording, or the test coverage based on your feedback.

Thanks!