Update playground link

src/pages/index.mdx

@@ -552,7 +552,7 @@ src/week05/tests/test_lecture.py ...         `, {language: "bash"}).value;
 <header id="landing">
   <h1 style={{marginTop:"20%"}}>Build without limits</h1>
   <nav>
-      <a href="https://demeter.run/code?repository=https://github.com/opshin/opshin-starter-kit.git&template=python&source=demeter&key=opshin-starter-kit">
+      <a href="https://playground.opshin.dev">
           <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" width="25px"><title>monitor-shimmer</title><path d="M21 16H3V4H21M21 2H3C1.89 2 1 2.89 1 4V16C1 17.11 1.9 18 3 18H10V20H8V22H16V20H14V18H21C22.11 18 23 17.11 23 16V4C23 2.89 22.1 2 21 2M15 5.5L14.38 6.87L13 7.5L14.38 8.13L15 9.5L15.63 8.13L17 7.5L15.63 6.87L15 5.5M10.5 7.5L9.41 9.91L7 11L9.41 12.09L10.5 14.5L11.6 12.09L14 11L11.6 9.91L10.5 7.5" /></svg>
           Playground
       </a>