v16.1.0

What's Changed

• fix(quiz): say when a scheduled quiz opens or closes on its start screen (backport #3225) by @mergify[bot] in #3226
• fix(lesson): show audio in the editor, accept m4a, and add audio assignments (backport #3227) by @mergify[bot] in #3228
• feat(lesson): play audio from a link and show Cloudflare Images links (backport #3231) by @mergify[bot] in #3232

Full Changelog: v16.0.0...v16.1.0