Switch Discourse deploy branch from master to main

site-cookbooks/kosmos_discourse/recipes/default.rb

@@ -10,7 +10,7 @@ repo = "https://github.com/discourse/discourse_docker"
 
 git deploy_path do
   repository repo
-  revision "master"
+  revision "main"
 end
 
 systemd_unit "discourse.service" do