Make sure the instance banner is never cropped (mastodon#10702)

Author: elegaanz

app/javascript/styles/mastodon/widgets.scss

@@ -4,7 +4,6 @@
 
   &__img {
     width: 100%;
-    height: 167px;
     position: relative;
     overflow: hidden;
     border-radius: 4px 4px 0 0;