Add integrity SHA-256 to externally loaded asset

Even though this POC is neither actively used nor maintained, this satisfies CodeQL and ensures the right resource is always loaded from the external URL.

pocs/distributed_collab/priv/static/index.html

@@ -24,7 +24,7 @@
     <h1>Collaborative JSON editing</h1>
     <div id="container"></div>
 
-    <script src="https://cdnjs.cloudflare.com/ajax/libs/fast-json-patch/3.1.1/fast-json-patch.js"></script>
+    <script src="https://cdnjs.cloudflare.com/ajax/libs/fast-json-patch/3.1.1/fast-json-patch.js" integrity="sha256-Qf9lvjtL7xCt5niiMAxwQDC+TowsJAqGo7aA4TEYQRw=" crossorigin="anonymous"></script>
 
     <script>
       const container = document.querySelector("#container");