convert GPLv3 license to SPDX

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

python-html2text.spec

@@ -7,10 +7,11 @@ also happens to be valid Markdown (a text-to-HTML format).
 
 Name:           python-%{upname}
 Version:        2024.2.26
-Release:        3%{?dist}
+Release:        4%{?dist}
 Summary:        %{common_sum}
 
-License:        GPLv3
+# Automatically converted from old format: GPLv3 - review is highly recommended.
+License:        GPL-3.0-only
 URL:            http://alir3z4.github.io/%{upname}
 Source0:        https://files.pythonhosted.org/packages/source/h/%{upname}/%{upname}-%{version}.tar.gz
 
@@ -79,6 +80,9 @@ popd
 
 
 %changelog
+* Mon Jul 29 2024 Miroslav Suchý <msuchy@redhat.com> - 2024.2.26-4
+- convert license to SPDX
+
 * Fri Jul 19 2024 Fedora Release Engineering <releng@fedoraproject.org> - 2024.2.26-3
 - Rebuilt for https://fedoraproject.org/wiki/Fedora_41_Mass_Rebuild