Update dependency @fortawesome/fontawesome-free to v6.4.0 (#225)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

package.json

@@ -17,7 +17,7 @@
   "dependencies": {
     "@creativecommons/vocabulary": "2020.11.3",
     "@fancyapps/fancybox": "3.5.7",
-    "@fortawesome/fontawesome-free": "6.3.0",
+    "@fortawesome/fontawesome-free": "6.4.0",
     "@next-theme/pjax": "0.6.0",
     "algoliasearch": "4.16.0",
     "animate.css": "3.1.1",