docs: update library version number in the playground

Author: josdejong

docs/index.html

@@ -448,7 +448,7 @@ <h3 class="title">Debugger</h3>
   </div>
 
   <script type="module">
-    import { jsonquery, stringify, parse, compile } from 'https://cdn.jsdelivr.net/npm/@jsonquerylang/jsonquery@3/lib/jsonquery.js'
+    import { jsonquery, stringify, parse, compile } from 'https://cdn.jsdelivr.net/npm/@jsonquerylang/jsonquery@4/lib/jsonquery.js'
     import { Formatter, FracturedJsonOptions } from 'https://cdn.jsdelivr.net/npm/fracturedjsonjs/+esm'
 
     window.jsonquery = { jsonquery, stringify, parse, compile }