fix: Fix pagination URLs if query string is already present

In the explore section, the base URL of the pagination links was
"https://example.com/explore" instead of "https://example.com/explore?topic=<id>".

Author: marienfressinaud

src/views/layouts/_pagination.html.twig

@@ -1,5 +1,5 @@
 {% if pagination.mustPaginate %}
-    {% set url = url ~ '?' in url ? '&' : '?' %}
+    {% set url = url ~ ('?' in url ? '&' : '?') %}
 
     <nav class="pagination">
         <ul class="pagination__container">