Fix avatar size in public page detailed status (#14140)

Regression from the inline-CSS changes

app/javascript/styles/mastodon/statuses.scss

@@ -140,6 +140,11 @@
 
   .detailed-status {
     padding: 15px;
+
+    .detailed-status__display-avatar .account__avatar {
+      width: 48px;
+      height: 48px;
+    }
   }
 
   .status {