Changelog:
- Added URL and do_not_copy options to video_duration.
- Moved _copy_video_to_video_dir() and _create_required_dirs_and_check_for_errors() to a new file, "videocopy.py" to facilitate the last point.
- Adjusted test_videoduration.py and test_videohash.py to facilitate this and ensure that it's tested properly.
- Removed support for Python versions <=3.7 to comply with yt-dlp support.