chore: update release to 4.3.12

include/emqx_release.hrl

@@ -29,7 +29,7 @@
 
 -ifndef(EMQX_ENTERPRISE).
 
--define(EMQX_RELEASE, {opensource, "4.3.11"}).
+-define(EMQX_RELEASE, {opensource, "4.3.12"}).
 
 -else.