[file-roller] build: Use SPDX format for license

[Jan Tojnar <jtojnar src gnome org>]

commit 08e019f2e3a3baf256ae4cee022abaa225de3311
Author: Jan Tojnar <jtojnar gmail com>
Date:   Sat Sep 17 11:36:10 2022 +0200

    build: Use SPDX format for license
    
    It is recommended by Meson.

 meson.build | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/meson.build b/meson.build
index 07bf97c7..8537cc35 100644
--- a/meson.build
+++ b/meson.build
@@ -1,7 +1,7 @@
 project(
   'file-roller',
   'c',
-  license: 'GPL2+',
+  license: 'GPL-2.0-or-later',
   version: '43.alpha',
   meson_version: '>=0.59',
 )