replace license with spdx.org variant

OBS-URL: https://build.opensuse.org/package/show/openSUSE:Factory/gimp-gap?expand=0&rev=18

gimp-gap.spec

@@ -36,7 +36,7 @@ Provides:       patched_build
 Conflicts:      %{name}-orig
 %endif
 Url:            http://www.gimp.org/
-License:        GPLv2
+License:        GPL-2.0
 Group:          Productivity/Multimedia/Video/Editors and Convertors
 Requires:       %{name}-lang = %{version}
 Summary:        GIMP Animation Package
@@ -76,7 +76,7 @@ sequences of single frames.
 %package orig
 Summary:        GIMP Animation Package
 Group:          Productivity/Multimedia/Video/Editors and Convertors
-License:        GPLv2
+License:        GPL-2.0
 Provides:       %{name} = %{version}-%{release}
 Obsoletes:      %{name} < %{version}-%{release}