chore: bump VERSION to 0.7.90 in master

so that we always have a higher version than the latest stable release
(0.7.x at the moment), giving us a buffer to further bump it to 0.8.9x as
we approach the 0.9.x series

VERSION

@@ -1 +1 @@
-0.6.0
+0.7.90

ui/main.qml

@@ -33,6 +33,7 @@ StatusWindow {
         Qt.application.displayName = qsTr("Status Desktop")
         Qt.application.organization = "Status"
         Qt.application.domain = "status.im"
+        Qt.application.version = aboutModule.getCurrentVersion()
         return Qt.application.displayName
     }
     visible: true