Change license of dul-web to GPLv2 or later, consistent with the rest of Dulwich. Thanks to Dave for licensing this as GPLv2+.

bin/dul-web

@@ -5,7 +5,7 @@
 # This program is free software; you can redistribute it and/or
 # modify it under the terms of the GNU General Public License
 # as published by the Free Software Foundation; version 2
-# of the License.
+# or (at your option) a later version of the License.
 #
 # This program is distributed in the hope that it will be useful,
 # but WITHOUT ANY WARRANTY; without even the implied warranty of