Upgrade Ruby to version 3.2.3

As usual, we're updating the bundler version in our Gemfile.lock so it
uses the one included in Ruby 3.2.3, and we're also updating the
`parser` gem so it supports this version.

Dockerfile

@@ -1,4 +1,4 @@
-FROM ruby:3.1.4-bullseye
+FROM ruby:3.2.3-bullseye
 
 ENV DEBIAN_FRONTEND noninteractive