update broken speaker img link

Author: tabcat

README.md

@@ -2,7 +2,7 @@
 
 <span>
   <a href="https://static.sfdict.com/audio/Z00/Z0026700.mp3" target="_blank" rel="noopener noreferrer">
-    <img src="https://camo.githubusercontent.com/b900202928a33c7574d271fb0ef74b60036da10fe81079709e87b86b939ed8e7/68747470733a2f2f6475636b6475636b676f2e636f6d2f6173736574732f69636f6e732f706c61792d627574746f6e2e737667" />
+    <img src="https://em-content.zobj.net/source/sony/336/speaker-high-volume_1f50a.png" />
   </a>
   zĭngk
 </span>