mkosi: Add missing SPDX line

diff --git a/mkosi.clean b/mkosi.clean
index bcd1ae42c89aedf51c433cf771aa37c0b18b78ff..dac2f1bf42153a7a6dbb28b67a6b8dbcbb5f905a 100755 (executable)
--- a/mkosi.clean
+++ b/mkosi.clean
@@ -1,4 +1,6 @@
 #!/bin/bash
+# SPDX-License-Identifier: LGPL-2.1-or-later
+
 set -e
 set -o nounset