Upgrade node-sass

[simurai]

This PR does the following suggested in #796 (comment).

FYI, according to sass/node-sass#2625 (comment), running npm audit --fix and committing package-lock.json should resolve this now.

$ npm audit --fix

found 1898 vulnerabilities (1853 low, 1 moderate, 44 high) in 2904 scanned packages
  run `npm audit fix` to fix 1768 of them.
  2 vulnerabilities require semver-major dependency updates.
  128 vulnerabilities require manual review. See the full report for details.

No changes to commit, so I ran:

$ npm audit fix

fixed 1768 of 1898 vulnerabilities in 2904 scanned packages
  128 vulnerabilities required manual review and could not be updated
  2 package updates for 2 vulnerabilities involved breaking changes
  (use `npm audit fix --force` to install breaking changes; or refer to `npm audit` for steps to fix these manually)

Is this ok to merge?

[vercel]

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[BinaryMuse]

Merged in latest changes from the main branch; if things still build and the site is fine I think it's 👍

[simurai]

if things still build and the site is fine I think it's 👍

Browsed a bit around on https://primer-css-git-npm-audit-fix.primer.vercel.app/css/ and things still look good.