[FIX] web_editor: make HR element not editable

task-2778511

closes odoo/odoo#89267

X-original-commit: af23ab272fcf9c33980679b0215be2fff0ea1a86
Signed-off-by: David Monjoie (dmo) <dmo@odoo.com>

addons/web_editor/static/lib/odoo-editor/src/utils/sanitize.js

@@ -166,7 +166,7 @@ class Sanitize {
         }
 
         // Sanitize media elements
-        if (isMediaElement(node)) {
+        if (isMediaElement(node) || node.tagName === 'HR') {
             // Ensure all media elements are tagged contenteditable=false.
             // we cannot use the node.isContentEditable because it can wrongly return false
             // when the editor is starting up ( first sanitize )