fix: start jiffy by emqx

apps/emqx/src/emqx.app.src

@@ -4,7 +4,7 @@
   {vsn, "5.0.0"}, % strict semver, bump manually!
   {modules, []},
   {registered, []},
-  {applications, [kernel,stdlib,gproc,gen_rpc,esockd,cowboy,sasl,os_mon,quicer]},
+  {applications, [kernel,stdlib,gproc,gen_rpc,esockd,cowboy,sasl,os_mon,quicer,jiffy]},
   {mod, {emqx_app,[]}},
   {env, []},
   {licenses, ["Apache-2.0"]},