Use WebP for Globby hello animation

Author: ceddc

README.md

@@ -2,7 +2,7 @@
 
 <p>
   <img src="./public/assets/globby-base.png" alt="Globby, the Tiny Assistant character" width="112" />
-  <img src="./public/assets/globby-hello.gif" alt="Globby hello animation" width="112" />
+  <img src="./public/assets/globby-hello.webp" alt="Globby hello animation" width="112" />
 </p>
 
 _Disclaimer: this code was 100% generated by AI. It may be good, it may be bad,