Ytb-downloader

What's Changed
* Update dependencies and remove support to python3.8. by zhiwei2017 in https://github.com/zhiwei2017/ytb_downloader/pull/7
* Change to poetry by zhiwei2017 in https://github.com/zhiwei2017/ytb_downloader/pull/8


**Full Changelog**: https://github.com/zhiwei2017/ytb_downloader/compare/v0.3.2...v0.4.0

Switch dependency from **youtube_dl** package to **yt_dlp** package, since **youtube_dl** has been inactive for more than 1 year and **yt_dlp** is an active folk of it and back compatible to it.

+ 2 introduced bulk downloading.
+ 3 enhanced documentation.