v2021.08.02

PR: hotfixes / master

Changelog

Fixed

• #3244 Exercise question randomization option default mismatched channel export default
• #3191 Editing channels in multiple tabs caused unexpected issues
• #3255 Resource preview drawer overflowed viewport
• #3254 Missing defensive check when clearing local data on sign out
• #3252 Drawer resize handling caused console errors

Changed

• #3236 Regex performance update in rich text editor for exercises
• #3233 Dev setup broke after Django upgrade
• #3257 Security update
• Code refactoring after automated analysis: #3066, #3221, #3220, #3222, #3219, #3223, #3229, #3211, #3230, #3232, #3228, #3231, #3242, #3238, #3241, #3239, #3240, #3237