convert GPLv3 license to SPDX

This is part of https://fedoraproject.org/wiki/Changes/SPDX_Licenses_Phase_4

volumeicon.spec

@@ -4,10 +4,11 @@
 
 Name:           volumeicon
 Version:        0.5.1
-Release:        16.20230208gitb034dd1%{?dist}
+Release:        17.20230208gitb034dd1%{?dist}
 Summary:        Lightweight volume control for the system tray
 
-License:        GPLv3
+# Automatically converted from old format: GPLv3 - review is highly recommended.
+License:        GPL-3.0-only
 URL:            https://github.com/Maato/%{name}
 Source0:        %{url}/archive/%{commit}.tar.gz#/%{name}-%{commit}.tar.gz
 # Source1 was borrowed from gnome-media package and adjusted for our needs
@@ -64,6 +65,9 @@ desktop-file-install --dir=%{buildroot}%{_sysconfdir}/xdg/autostart %{SOURCE1}
 %{_datadir}/man/man5/%{name}.5*
 
 %changelog
+* Mon Jul 29 2024 Miroslav Suchý <msuchy@redhat.com> - 0.5.1-17.20230208gitb034dd1
+- convert license to SPDX
+
 * Sat Jul 20 2024 Fedora Release Engineering <releng@fedoraproject.org> - 0.5.1-16.20230208gitb034dd1
 - Rebuilt for https://fedoraproject.org/wiki/Fedora_41_Mass_Rebuild