replace license with spdx.org variant

OBS-URL: https://build.opensuse.org/package/show/openSUSE:Factory/gnucash?expand=0&rev=39

gnucash.spec

@@ -20,7 +20,7 @@
 Name:           gnucash
 Version:        2.4.7
 Release:        1
-License:        GPLv2+
+License:        GPL-2.0+
 Summary:        Personal Finance Manager
 Url:            http://www.gnucash.org/
 Group:          Productivity/Office/Finance
@@ -78,7 +78,7 @@ use, but is backed with double-entry accounting principles to
 ensure balanced books.
 
 %package devel
-License:        GPLv2+
+License:        GPL-2.0+
 Summary:        Personal Finance Manager
 Group:          Development/Libraries/C and C++
 Requires:       %{name} = %{version}