[calls] notifier: Add notification category

[Evangelos Ribeiro Tzaras <devrtz src gnome org>]

commit a1fa33c7afb1fbfdfd37b3a57333cbe719380024
Author: Guido Günther <agx sigxcpu org>
Date:   Mon Aug 2 12:22:01 2021 +0200

    notifier: Add notification category
    
    This helps shells to adjust the kind of haptic/visual/audio
    feedback for the notification.

 src/calls-notifier.c | 3 +++
 1 file changed, 3 insertions(+)
---
diff --git a/src/calls-notifier.c b/src/calls-notifier.c
index 1c71f6a7..6d2086f4 100644
--- a/src/calls-notifier.c
+++ b/src/calls-notifier.c
@@ -54,6 +54,9 @@ notify (CallsNotifier *self, CallsCall *call)
   const char *number;
   gboolean got_number;
 
+#if GLIB_CHECK_VERSION(2,70,0)
+  g_notification_set_category (notification, "x-gnome.call.unanswered");
+#endif
   contact = calls_call_get_contact (call);
   // TODO: We need to update the notification when the contact name changes
   name = calls_best_match_get_name (contact);