Bugfixes
- Don't use brotli if import fails
- Fix author_url not prefixed in subscriptions page (it had a link to youtube.com rather than staying within youtube-local)
- Fix channel pages and subscriptions failing with 'Unknown error'
- Fix old videos appearing in subscriptions when channel deletes vids
- Support integer-only ?t param
- Use Python 3.7.6 so it will work on Windows Vista
Other
- extract_channel_info: Improve error extraction
- extract_items: Handle case where continuation has multiple [something]Continuation renderers, all of which are junk except one