Pytchat

Fix
Retry to fetch data when failed to parse video info.

+ Update CLI progress bar - show progress of rendering.

Fix
+ Fixed a case where video information could not be extracted correctly. (17)

Fix
+ Fixed requirements.txt for setup.

+ Replaced the http client with [httpx](https://github.com/encode/httpx) instead of requests / aiohttp. (#13)
The default communication behavior is now via http2. (Except in some cases)

CLI :
+ Show progress bar while extracting chats.
+ New option `--save_error_data`. If this option is specified, the error data will be saved as a `.dat` file when the error occurs. (CLI only)

Fix
CLI:
Fixed an error in getting video information. (Issue 14)
Fixed an error occurring when specifying a url with video id.