[FIX] website: fix the dynamic snippets rendered content

Since commit [1], which updates jQuery to version 3.6.3, when dropping a
dynamic snippet (Events, Blog Posts), it appears broken. This happens
because in jQuery 3.5.0, the `htmlPrefilter` function (which is called
when the dynamic snippet content is rendered) has been modified.

The dynamic snippets are broken because auto-closed tags are contained
in the data that are fetched from the server and without the jQuery
regex to fix them, they are never closed properly, which breaks the
rendering. Indeed, the `etree.tostring(...)` function auto-closes the
tags of elements having no content when no method is specified as a
parameter.

This commit prevents auto-closed tags to appear in the data sent by the
server when rendering the dynamic snippets, by enforcing the fact that
they will be used as HTML.

[1]: https://github.com/odoo/odoo/commit/ae1cd3d5bb99b9835501144522b71f152aaf8e34

task-3199318

closes odoo/odoo#116929

X-original-commit: f6cbec8d0116305041f018870ab63e26c8cbef41
Signed-off-by: Quentin Smetz (qsm) <qsm@odoo.com>

addons/website/models/website_snippet_filter.py

@@ -75,7 +75,7 @@ class WebsiteSnippetFilter(models.Model):
             records=records,
             is_sample=is_sample,
         ))
-        return [etree.tostring(el, encoding='unicode') for el in html.fromstring('<root>%s</root>' % str(content)).getchildren()]
+        return [etree.tostring(el, encoding='unicode', method='html') for el in html.fromstring('<root>%s</root>' % str(content)).getchildren()]
 
     def _prepare_values(self, limit=None, search_domain=None):
         """Gets the data and returns it the right format for render."""