Upgrade ruby version & update SCSS imports

[smoreface]

This PR does the following:

• Update the ruby version to 3.4 to avoid deprecations coming with3.2.2: https://www.ruby-lang.org/en/downloads/branches/
• Add new dependencies to gemspec file to account for dependent gems that are no longer included in version 3.4 or 3.5 of Ruby.
• Update the SCSS files to use @use statements instead of @import as indicated by https://sass-lang.com/documentation/breaking-changes/import/. This also required some reformatting of the files:
  • Make the variables in styles.scss part of a "with" statement so they would be imported by the _wax.scss file properly.
  • Set default variable values in the _wax.scss file that could be overridden by the styles.scss file to match the way imports work now.

The changes in this PR were tested by:

• Building locally with --trace and identifying and fixing any errors that appeared.
• Building with a Netlify deploy (which did require hardcoding the node version in an environment variable due to some dependencies in a chain somewhere)
• Running the tasks after the changes and accounting for any errors that resulted from that.

Some notes:

• This is a backwards compatible change but it might still make sense to release as a new version of wax because folks will need to rerun bundle install to recreate the gemfile lock to use this version. I'm not sure how much this will matter!
• It might make more sense to specify a more specific version of Ruby but they seem to follow semantic versioning practices so it felt safe to specify only 3.4 instead of a more specific version.
• It might make sense to declare the variables in styles.scss directly in _wax.scss given the way that imports need to be declared now, but there are still a few things directly stated in styles.scss so I didn't reorganize anything.
• The wiki would need to be updated after this PR is merged (if it is merged!) — I am happy to open a PR for that as well.