file-transfer: Fix SpiceFileTransferTask::file_stream leak

g_file_read_finish() is (transfer full) so we must release the ref
we got in _dispose() as it's not done anywhere else in the code.

Acked-by: Victor Toso <victortoso@redhat.com>

src/spice-file-transfer-task.c

@@ -588,6 +588,7 @@ spice_file_transfer_task_dispose(GObject *object)
     SpiceFileTransferTask *self = SPICE_FILE_TRANSFER_TASK(object);
 
     g_clear_object(&self->file);
+    g_clear_object(&self->file_stream);
 
     G_OBJECT_CLASS(spice_file_transfer_task_parent_class)->dispose(object);
 }