chore: Upgrade rails and ruby versions (#2400)

ruby version: 3.0.2
rails version: 6.1.4

deployment/setup_18.04.sh

@@ -43,8 +43,8 @@ RAILS_ENV=production
 sudo -i -u chatwoot << EOF
 rvm --version
 rvm autolibs disable
-rvm install "ruby-2.7.3"
-rvm use 2.7.3 --default
+rvm install "ruby-3.0.2"
+rvm use 3.0.2 --default
 
 git clone https://github.com/chatwoot/chatwoot.git
 cd chatwoot