chore(deps): bump @fortawesome/fontawesome-free from 6.4.0 to 6.4.2

Bumps [@fortawesome/fontawesome-free](https://github.com/FortAwesome/Font-Awesome) from 6.4.0 to 6.4.2.
- [Release notes](https://github.com/FortAwesome/Font-Awesome/releases)
- [Changelog](https://github.com/FortAwesome/Font-Awesome/blob/6.x/CHANGELOG.md)
- [Commits](FortAwesome/Font-Awesome@6.4.0...6.4.2)

---
updated-dependencies:
- dependency-name: "@fortawesome/fontawesome-free"
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

package-lock.json

@@ -3,7 +3,7 @@
   "version": "3.2.6",
   "private": true,
   "dependencies": {
-    "@fortawesome/fontawesome-free": "^6.4.0",
+    "@fortawesome/fontawesome-free": "^6.4.2",
     "highlight.js": "^11.8.0",
     "katex": "^0.16.8",
     "uikit": "^3.16.26",