Rename v4 FontAwesome icons to match v5/v6 name

While FontAwesome provides aliases for all icons, we switch to the new names for consistency. See all changes at:
https://fontawesome.com/docs/web/setup/upgrade/upgrade-from-v4#icons-renamed-since-version-4

app/assets/javascripts/editor/participantsupport.js.erb

@@ -6,7 +6,7 @@ CodeOceanEditorFlowr = {
         '<div class="card-title mb-0">' +
           '<a class="collapsed" data-toggle="collapse" data-parent="#flowrHint" href="#{{collapseId}}" aria-expanded="false" aria-controls="{{collapseId}}">' +
             '<div class="clearfix" role="button">' +
-              '<i class="fa" aria-hidden="true"></i>' +
+              '<i class="fa-solid" aria-hidden="true"></i>' +
               '<span>' +
               '</span>' +
             '</div>' +