Upgrade sass to support Node 16+

[hussam-i-am]

This pull request to the frontend package updates dependencies and package versions, and uses the sass:math module to update variable and property calculations in various SCSS files.

• frontend/package.json: Updated dependencies and package version. (Update dependencies and package version in frontend/package.json)
• frontend/app/styles/bitters/_variables.scss: Updated calculation for $small-spacing using the sass:math module. (Update variable calculation, Import module)
• frontend/app/styles/bitters/_forms.scss: Imported and used the math module to update property calculations for padding, margin-right, and margin-bottom in various selectors. (Import and use math module to update property calculations in _forms.scss)

[Tonkpils]

✨ this looks straight forward although I'm not super familiar with the upgrade process for sass. It looks like there's some deprecation notices in the CI run https://github.com/rubyforgood/Flaredown/actions/runs/6397479951/job/17365494297?pr=677#step:6:33

Would you mind addressing those?

It's encouraging that all tests seems to pass now for all the node versions. I'll give this a spin locally and in staging to see if things are working as expected and get back to you when I do 🙇

[hussam-i-am]

@Tonkpils I believe the notices are for usages from within bower_components for bourbon/neat. I tried upgrading/porting those to npm but didnt have much luck. Will try again as a followup PR, but figured to leave this as is so it could move ahead independently