Update LICENSE

add SPDX

#6 yet again

LICENSE

@@ -2,7 +2,7 @@ UNICODE LICENSE V3
 
 COPYRIGHT AND PERMISSION NOTICE
 
-Copyright © 2022-2023 Unicode, Inc.
+Copyright © 2022-2024 Unicode, Inc.
 
 NOTICE TO USER: Carefully read the following legal agreement. BY
 DOWNLOADING, INSTALLING, COPYING OR OTHERWISE USING DATA FILES, AND/OR
@@ -37,3 +37,5 @@ Except as contained in this notice, the name of a copyright holder shall
 not be used in advertising or otherwise to promote the sale, use or other
 dealings in these Data Files or Software without prior written
 authorization of the copyright holder.
+
+SPDX-License-Identifier: Unicode-3.0