chore: Upgrade to Ruby 3.2.1 & Rails 6.0

* chore: upgrade to rails 6.0

* chore: upgrade ruby to 3.2.1

* chore: upgrade bundler

* chore: upgrade execjs

* chore: upgrade to rails 6.1

* chore: switch to sentry-ruby from raven

* chore: add extra platforms to gemfile

app/views/layouts/application.html.haml

@@ -58,4 +58,3 @@
               Powered by #{link_to "Postal", "https://postalserver.io", target: '_blank'} #{Postal.version}.
             %li= link_to "Documentation", "https://docs.postalserver.io", target: '_blank'
             %li= link_to "Ask for help", "https://discussions.postalserver.io", target: '_blank'
-