[prepare] use SPDX license identifer

PKGBUILD

@@ -15,7 +15,7 @@ pkgrel=1
 pkgdesc="Virtual Terminal Emulator widget with Fedora patches"
 arch=(x86_64)
 url="https://wiki.gnome.org/Apps/Terminal/VTE"
-license=(LGPL)
+license=(GPL-3.0-or-later AND LGPL-3.0-or-later and MIT-open-group AND CC-BY-4.0)
 makedepends=(
   cairo
   fribidi