Set JSON type attr on config script tag

Without this, the browser will try to parse the client's config script element
as JS when it is inserted into the page, causing a syntax error to be reported
in the console.

Author: robertknight

via/static/scripts/video_player/components/HypothesisClient.tsx

@@ -19,7 +19,9 @@ export default function HypothesisClient({
   const clientConfig = JSON.stringify(config);
   return (
     <>
-      <script className="js-hypothesis-config">{clientConfig}</script>
+      <script type="application/json" className="js-hypothesis-config">
+        {clientConfig}
+      </script>
       <script src={src} />
     </>
   );