Wafer 0.15.0

This is the first release of the 0.15 series

Changes

Update to support crispy-forms v2
Update to use bootstrap 5
- Drop direct popper.js dependency as it is no longer needed
Update to latest fontawesome packages
Add login & registration date columns to admin user view
More translataions
Fix several assumptions in the schedule tests to make them more robust against database and ical version differences
Add less blank pages for when no talks are submitted / visible
Added more blocks to some templates to make them easier to override