versioned_graph/commit

fixed: missing library import, caught by xref

diff --git a/lib/gv_replay.pl b/lib/gv_replay.pl
index f8011b8..be861e5 100644
--- a/lib/gv_replay.pl
+++ b/lib/gv_replay.pl
@@ -5,6 +5,8 @@
 	    gv_restore_git_from_rdf/2
 	  ]).
 
+:- use_module(library(semweb/rdf_db)).
+
 :- use_module(graph_version).
 :- use_module(gv_git_objects).
 :- use_module(gv_git_io).