Handle errors that may occur during thumbnail deletion

[daniil-berg]

We already catch and log any OSError during video file deletion in the StorageFileController.remove_files method:

videbo/src/videbo/storage/file_controller.py

Lines 381 to 386 in e7b53e0

	await self.remove_thumbnails(file_hash)
	try:
	await self.remove_video(file)
	except OSError as e:
	log.error(f"Unexpected failure to delete video {file}: {e!r}")
	continue

However the .remove_thumbnails method currently simply swallows any errors that may occur, when Path.unlink is called on a thumbnail path. Since gather already collects exceptions, we should simply log them there.