* Ported to GTK 4

* Updated README dependencies

* Updated GitHub actions

* Added blueprint-compiler to README dependencies

* Fixed expanded_group not being set to null when group only contains a single notification

* Added a overlay close button for grouped notifications, just like regular notifications

* Fixed control center kb shortcuts not always working

* Fixed Notification sizing in Control Center

When adding a large notification with a body image and actions, and add
a seperate non-grouped notification, the first notification would take
up more space than needed

* Simplified Notification Group offset calculation

* Limit the control center height to the monitors height

* Fixed vala-lint issues

* Fixed MPRIS background not using album art gicon

* Show --skip-system-css in --help print

* Fixed CC adaptive height being short with fit-to-screen enabled

* Fixed grouped notifications not notifying CC that it's not the expanded one

* Fixed notification groups focus being buggy and not visually visible

* Fixed notification focus resetting to the top when removing the last notification