Front Page: Call for speakers not showing up

[mariobehling]

Events with an open call for speakers are not showing up on the front page. Right now the Nextcloud event should be showing up here for example.

This is similar to #4481

[iamareebjamal]

Same as #4481, will be fixed in #4653

[Haider8]

Yes, both Nextcloud Conference 2020 and OpenTechSummit Thailand are visible after #4653 fix.