trim more alt texts

src/_includes/partials/sidebar.njk

@@ -3,5 +3,5 @@
 </a>
 <div class="sidebar-contents">
     {% include 'partials/navigation.njk' %}
-    <img src="/_assets/img/143.gif" alt="The character Yui Hirasawa from the anime K-on floating ina cube of water in a inner tube. The image has been rendered in a chibi, pixel art style with a short looping animation of Yui floating up and down."/>
+    <img src="/_assets/img/143.gif"/>
 </div>