fix(notifications): better handle singular and plural hours and minutes

Author: wash2

cosmic-applet-notifications/i18n/en/cosmic_applet_notifications.ftl

@@ -1,3 +1,9 @@
-hours-ago = {$duration} Hours Ago
-minutes-ago = {$duration} Minutes Ago
+hours-ago = { NUMBER($duration) -> 
+    [1] 1 Hour Ago
+    *[other] {$duration} Hours Ago
+}
+minutes-ago = { NUMBER($duration) -> 
+    [1] 1 Minute Ago
+    *[other] {$duration} Minutes Ago
+}
 clear-all = Clear All Notifications