fix: map-get deprecated in scss

[hivenet-tomcrammond]

Hi!

I noticed that the scss generation using sass 1.85.0 seems to be failing. According to the Heads Up in this document the map-get() function has become deprecated in due to the switch to the new import system. Unfortunately was not able to determine when this came into effect 🤷‍♂️

Making the changes in this PR resolved the issue for me. Thought it would be helpful for others as well :)

For any troubled developers reading this, know that you can take advantage of these changes without forking the library with the handy-dandy templates option! Just copy the scss.hbs file to your repo, add this PRs' changes to it and point to it using the templates option in the fantasticon config. Like so:

module.exports = {
   ...
   templates: {
     scss: 'path/to/map-get-fix-template.scss.hbs'
   },
   ...
}