build(deps): bump @fortawesome/fontawesome-free from 5.15.3 to 5.15.4

Bumps [@fortawesome/fontawesome-free](https://github.com/FortAwesome/Font-Awesome) from 5.15.3 to 5.15.4.
- [Release notes](https://github.com/FortAwesome/Font-Awesome/releases)
- [Changelog](https://github.com/FortAwesome/Font-Awesome/blob/master/CHANGELOG.md)
- [Commits](FortAwesome/Font-Awesome@5.15.3...5.15.4)

---
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": "2.12.1",
   "private": true,
   "dependencies": {
-    "@fortawesome/fontawesome-free": "^5.15.3",
+    "@fortawesome/fontawesome-free": "^5.15.4",
     "highlight.js": "^11.2.0",
     "katex": "^0.13.13",
     "uikit": "^3.7.2",