3.20.4
======
* Free old backgrounds immediately [Hyungwon; #766353]
* Adjust to flatpak PermissionStore API changes [Florian; #766598]
* calendar: Only hide dismissed occurrence of recurring event [Florian; #748226]

Contributors:
  Hyungwon Hwang, Florian Müllner

Translations:
  Bruce Cowan [en_GB], Piotr Drąg [pl]