chore: update to ruby 4

[gildesmarais]

This pull request upgrades the project to use Ruby 4.0.0 and updates the Docker environment accordingly. The main focus is on ensuring compatibility with the latest Ruby version across both development and production environments.

Ruby version upgrade:

• Updated the Ruby version in .ruby-version from 3.4.0 to 4.0.0 to standardize development environments on the latest Ruby release.

Docker environment updates:

• Changed the base image in both the build and runtime stages of the Dockerfile from ruby:3.4.7-alpine3.21 to ruby:4.0.0-alpine3.23 to align with the new Ruby version and ensure consistency in containerized deployments. [1] [2]

Minor test file cleanup:

• Added a blank line in spec/routes/auto_source_spec.rb for formatting consistency.

TODOs

• WF: nokogiri release
• WF: Add Ruby 4.0.0 support tisba/faraday-follow-redirects#61