reuse fix

Author: matt-beanland

.igniter.exs

@@ -1,3 +1,7 @@
+# SPDX-FileCopyrightText: 2025 diffo_example contributors <https://github.com/diffo-dev/diffo_example/graphs.contributors>
+#
+# SPDX-License-Identifier: MIT
+
 # This is a configuration file for igniter.
 # For option documentation, see https://hexdocs.pm/igniter/Igniter.Project.IgniterConfig.html
 # To keep it up to date, use `mix igniter.setup`