Fix setting Slack token

src/metabase/api/slack.clj

@@ -16,6 +16,7 @@
     ;; just check that channels.list doesn't throw an exception (that the connection works)
     (when-not config/is-test?
       (slack/GET :channels.list, :exclude_archived 1, :token slack-token))
+    (slack/slack-token slack-token)
     {:ok true}
     (catch clojure.lang.ExceptionInfo info
       {:status 400, :body (ex-data info)})))