fix(html): Fix issue where firefox would throw a charset error

public/index.html

@@ -13,6 +13,7 @@
         <link rel="manifest" href="./manifest.webmanifest">
         <link rel="mask-icon" href="/safari-pinned-tab.svg" color="#5bbad5">
         <link rel="stylesheet" type="text/css" href="./res/css/xterm.css" media="screen" />
+        <meta charset="utf-8"/>
         <style>
             .CanvasYo {
                 background: red;