Sticker-convert

- Compatibility with telegram api 7.2
- FIx downloading and uploading telegram stickers (140)
- Support for sticker pack with mixed sticker formats
- Maximum sticker count is 120 for both static and animated sticker packs
- FIx telegram emoji pack maximum sticker count to 200 (was 120)
- Use custom fork of signalstickers-client
- Update dependencies

- Fix bug where animated stickers are not accepted by WhatsApp since v2.8.0
- It was noted that pywebp would collapse all frames.
- aed005b attempted to fix this by creating webp with variable frame duration.
- However, the webp created would not be accepted by WhatsApp.
- Solution: If there is duplicated frame, use Pillow to save WebP if available, or else use pywebp and display warning.
- Better compliance with wastickers format
- Fix compression success not shown if success on step 0

- Add option for padding (`--padding-percent`)
- Allow auto retry for telegram down/upload
- Fix deadlock if no files to compress
- Fix hanging during cancel job on Windows

- Fix job random hanging
- Remove opt_comp_experiment
- Code cleanup

- Fix first frame getting dropped
- Fix importing gif/webp/apng with variable frame durations
- Calculate mean color frame by frame instead of combining to one large array, saving memory
- Fix webp collapsing same frames, causing incorrect timestamps
- Avoid overwritting frame in pyav
- Remove wheel as build dependency

- Fix not trying to compress lowest step
- Pad odd dimension video in pyav instead of resizing and causing blur
- Fix png being decoded by pyav
- Decode gif with pillow