Add SPDX-License-Identifier to extract-translation-templates.sh

Signed-off-by: Suguru Hirahara <acioustick@noreply.codeberg.org>

i18n/bin/extract-translation-templates.sh

@@ -1,6 +1,8 @@
 #!/bin/bash
 
 # SPDX-FileCopyrightText: 2024 Slavi Pantaleev <slavi@devture.com>
+#
+# SPDX-License-Identifier: AGPL-3.0-or-later
 
 # This script extracts translation templates (original English strings) into the `translation-templates/` directory.
 # These templates are later used to generate locale files for each language in the `locales/` directory.