imagefreeze: Set seqnum from segment too

This is the right behavior, setting from seeks is also OK but we should take the seqnums from segment into account too

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/9015>

subprojects/gst-plugins-good/gst/imagefreeze/gstimagefreeze.c

@@ -643,6 +643,7 @@ gst_image_freeze_sink_event (GstPad * pad, GstObject * parent, GstEvent * event)
       /* fall-through */
     case GST_EVENT_SEGMENT:
       GST_DEBUG_OBJECT (pad, "Dropping event");
+      self->seqnum = GST_EVENT_SEQNUM (event);
       gst_event_unref (event);
       ret = TRUE;
       break;