Closes #11826: RSS feed widget (#11976)

* Add feedparser as a dependency

* Introduce RSSFeedWidget

* Clean up widget templates

netbox/templates/extras/dashboard/widget_add.html

@@ -4,6 +4,7 @@
   {% csrf_token %}
   <div class="modal-header">
     <h5 class="modal-title">Add a Widget</h5>
+    <button type="button" class="btn-close" data-bs-dismiss="modal" aria-label="Close"></button>
   </div>
   <div class="modal-body">
     {% block form %}