community/avizo: fix license

It's not clearly specified in upstream, GPL-3.0-only is based on
Arch Linux and Void packages.

community/avizo/APKBUILD

@@ -6,7 +6,7 @@ pkgrel=0
 pkgdesc="A neat notification daemon"
 url="https://github.com/misterdanb/avizo"
 arch="all"
-license="GPL-3.0"
+license="GPL-3.0-only"
 makedepends="
 	gobject-introspection-dev
 	gtk+3.0-dev