5.0.3

Bug fixes

Websocket listener failed to read headers X-Forwared-For and X-Forwarded-Port 8415
Deleted cluster_singleton from MQTT bridge config document. This config is no longer applicable in 5.0 8407
Fix emqx/emqx:latest docker image publish to use the Erlang flavor, but not Elixir flavor 8414
Changed the exp field in JWT auth to be optional rather than required to fix backwards compatability with 4.X releases. 8425

Improve the speed of dashboard's HTTP API routing rule generation, which sometimes causes timeout 8438