Upgrade Ruby from v3.2.1 -> v3.2.3

This is the latest patch version of Ruby v3.2.

We've been seeing the following warning in our Heroku deployments, e.g.
in this staging deployment [1]:

    There is a more recent Ruby version available for you to use:

    3.2.3

    The latest version will include security and bug fixes. We always recommend
    running the latest version of your minor release.

    Please upgrade your Ruby version.

    For all available Ruby versions see:
     https://devcenter.heroku.com/articles/ruby-support#supported-runtimes

The Ruby version in `Gemfile` and the base image in `Dockerfile` are
only specified in terms of the minor version (i.e. v3.2) rather than the
patch version, so there's no need to change them. Furthermore the
`ruby:3.2-slim-bullseye` base image has already been updated to include
v3.2.3 [2].

[1]: https://dashboard.heroku.com/apps/editor-api-staging/activity/builds/f9360560-9d26-487b-8258-cf84906055bf
[2]: docker-library/ruby@c473741

Author: floehopper

.ruby-version

@@ -1 +1 @@
-ruby-3.2.1
+ruby-3.2.3

.tool-versions

@@ -1 +1 @@
-ruby 3.2.1
+ruby 3.2.3

Gemfile.lock

@@ -502,7 +502,7 @@ DEPENDENCIES
   webmock
 
 RUBY VERSION
-   ruby 3.2.1p31
+   ruby 3.2.3p157
 
 BUNDLED WITH
    2.4.7