fix(acl): fix wrong default ACL rules

apps/emqx_authz/etc/acl.conf

@@ -23,7 +23,7 @@
 %% -type(rule() :: {permission(), who(), access(), topics()} | {permission(), all}).
 %%--------------------------------------------------------------------
 
-{allow, {username, "^dashboard?"}, subscribe, ["$SYS/#"]}.
+{allow, {username, {re, "^dashboard?"}}, subscribe, ["$SYS/#"]}.
 
 {allow, {ipaddr, "127.0.0.1"}, all, ["$SYS/#", "#"]}.