New features:
1. Translation updates: Bringing Russian and Brazilian Portuguese to 100%.
1. New languages with incomplete translations: Belarusian, German, French, Indonesian, Malayalam, Norwegian Bokmål.
1. Include links to events in the iCal feed.
1. Add schedule JSON export.
1. Add support for Python 3.9.
1. Management command to export talk titles, speakers, and video reviewers.
Bug fixes:
1. Settings documentation matches reality, again.
1. Fix a bug in the Pentabarf XML feed, where entries were missing `<end>` tags.
Minor changes:
1. Speakers are now listed by talk type.
1. Bump popper.js version to 1.16.x.
1. Drop support for Python 3.5, as it is End of Life.
1. Drop support for Django < 2.2, as it is End of Life.
1. Drop dependency on `psycopg2-binary` and the `mdx` packages, these are optional.
1. Improved installation documentation.
1. Improved strings for translation (replacing positional variables with named variables).