fix: include emqx_utils in distribution

rebar.config.erl

@@ -391,6 +391,7 @@ relx_apps(ReleaseType, Edition) ->
             {covertool, load},
             % started by emqx_machine
             {system_monitor, load},
+            emqx_utils,
             emqx_http_lib,
             emqx_resource,
             emqx_connector,