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

lib/postal/tracking_middleware.rb

@@ -44,7 +44,7 @@ module Postal
       rescue StandardError => e
         # Somethign else went wrong. We don't want to stop the image loading though because
         # this is our problem. Log this exception though.
-        Raven.capture_exception(e) if defined?(Raven)
+        Sentry.capture_exception(e) if defined?(Sentry)
       end
 
       source_image = request.params["src"]