rpcserver: remove unnecessary conversion

rpcserver.go

@@ -2815,7 +2815,7 @@ func (r *rpcServer) GetInfo(_ context.Context,
 		Uris:                uris,
 		Alias:               nodeAnn.Alias.String(),
 		Color:               routing.EncodeHexColor(nodeAnn.RGBColor),
-		BestHeaderTimestamp: int64(bestHeaderTimestamp),
+		BestHeaderTimestamp: bestHeaderTimestamp,
 		Version:             build.Version() + " commit=" + build.Commit,
 		CommitHash:          build.CommitHash,
 		SyncedToGraph:       isGraphSynced,