Pin DOMPurify to exact version 3.4.5

Author: alexander-yevsyukov

site/layouts/_partials/oss-licenses/licenses.html

@@ -48,7 +48,9 @@
 
 <!-- HTML sanitizer required by `assets/js/pages/oss-licenses.js`
 to prevent XSS when injecting remote Markdown as HTML. -->
-<script src="https://cdn.jsdelivr.net/npm/dompurify@3/dist/purify.min.js"
+<script src="https://cdn.jsdelivr.net/npm/dompurify@3.4.5/dist/purify.min.js"
+        integrity="sha384-7FXQySTrDscwsLx1i8RIqZM/JHoUVstx4CuL2b7tziI4Glhp3/3dm/j3qUTheVXE"
+        crossorigin="anonymous"
         type="text/javascript"
         charset="utf-8"></script>