Bump Conduit client version number

Summary: Should have been part of D3934.

Test Plan:
  $ arc diff

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D4076

Author: vrana

src/workflow/ArcanistBaseWorkflow.php

@@ -230,7 +230,7 @@ public function forceConduitVersion($version) {
    * @task conduit
    */
   public function getConduitVersion() {
-    return nonempty($this->forcedConduitVersion, 5);
+    return nonempty($this->forcedConduitVersion, 6);
   }