chore: bust backers image cache

BACKERS.md

@@ -4,6 +4,6 @@ Vue.js is an MIT-licensed open source project with its ongoing development made
 
 <p align="center">
   <a target="_blank" href="https://sponsors.vuejs.org/backers.svg">
-    <img alt="sponsors" src="https://sponsors.vuejs.org/backers.svg">
+    <img alt="sponsors" src="https://sponsors.vuejs.org/backers.svg?v1">
   </a>
 </p>