Add license information to files for matrix-registration

This commit adds copyright attributions in SPDX to the files for matrix-registration following REUSE's specification.

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

roles/custom/matrix-registration/tasks/setup_install.yml

@@ -1,3 +1,13 @@
+# SPDX-FileCopyrightText: 2020 - 2024 Slavi Pantaleev
+# SPDX-FileCopyrightText: 2020 Stuart Mumford
+# SPDX-FileCopyrightText: 2022 Marko Weltzer
+# SPDX-FileCopyrightText: 2022 Jim Myhrberg
+# SPDX-FileCopyrightText: 2022 Nikita Chernyi
+# SPDX-FileCopyrightText: 2022 Sebastian Gumprich
+# SPDX-FileCopyrightText: 2024 David Mehren
+#
+# SPDX-License-Identifier: AGPL-3.0-or-later
+
 ---
 
 - ansible.builtin.set_fact: