[fix] Removes `/>` ending tags for void HTML elements

Removes ``/>`` ending tags for void elements [1] and replaces them with ``>``.
Part of the larger cleanup to cleanup invalid HTML throughout the codebase [2].

[1] https://html.spec.whatwg.org/multipage/syntax.html#void-elements
[2] https://github.com/searxng/searxng/issues/3793

searx/templates/simple/preferences/cookies.html

@@ -1,7 +1,7 @@
 <p class="text-muted">
   {{- _('This is the list of cookies and their values SearXNG is storing on your computer.') }}
-  <br />{{- _('With that list, you can assess SearXNG transparency.') -}}
-  <br />{{- '' -}}
+  <br>{{- _('With that list, you can assess SearXNG transparency.') -}}
+  <br>{{- '' -}}
 </p>
 {% if cookies %}
   <table class="cookies">