avfdeviceprovider: do not leak the properties

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/3268>

subprojects/gst-plugins-bad/sys/applemedia/avfdeviceprovider.m

@@ -76,11 +76,16 @@ gst_av_capture_device_get_props (AVCaptureDevice *device)
     "avf.has_torch", G_TYPE_BOOLEAN, [device hasTorch],
   NULL);
 
+  g_free (unique_id);
+  g_free (model_id);
+
 #if !HAVE_IOS
   char *manufacturer = g_strdup ([[device manufacturer] UTF8String]);
   gst_structure_set (props,
     "avf.manufacturer", G_TYPE_STRING, manufacturer,
   NULL);
+
+  g_free (manufacturer);
 #endif
 
   return props;