- breaking: make `--frames_dir` optional. by default, frame files are not saved. 9
- breaking: output json schema changed:
- `.frames_dir` is deleted
- `.frames_step` is deleted
- `.frames[].frame_files` is deleted, `.frames[].frame_index` is added instead.
**Full Changelog**: https://github.com/kj-9/ocrvid/compare/v0.4.0...v0.5.0