minor change.

dune.module

@@ -2,5 +2,5 @@ Module: dune-fem-dg
 Version: 3.0
 Maintainer: dune@mathematik.uni-freiburg.de
 Whitespace-Hook: Yes
-Depends: dune-fem (>=2.5 )
+Depends: dune-fem (>=2.5 ) dune-optim ( >= 2.5 )
 Sources: dune