migrate license to SPDX

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

python-avocado.spec

@@ -299,7 +299,7 @@ Common files (such as configuration) for the Avocado Testing Framework.
 
 %package -n python3-avocado-plugins-output-html
 Summary: Avocado HTML report plugin
-License: GPLv2+ and MIT
+License: GPL-2.0-or-later AND MIT
 Requires: python3-avocado == %{version}-%{release}
 
 %description -n python3-avocado-plugins-output-html
@@ -434,7 +434,7 @@ examples of how to write tests on your own.
 
 %package -n python-avocado-bash
 Summary: Avocado Test Framework Bash Utilities
-License: GPLv2+ and GPLv2
+License: GPL-2.0-or-later AND GPL-2.0-only
 Requires: python-avocado-common == %{version}-%{release}
 
 %description -n python-avocado-bash