fix: keep footer at bottom on short pages

Agent-Logs-Url: https://github.com/dsaub/proyecto-final/sessions/b935601c-c133-451b-9de5-556afef7178f

Co-authored-by: dsaub <54474838+dsaub@users.noreply.github.com>

tienda/templates/tienda/base.html

@@ -155,7 +155,7 @@
 
         {% cache 500 footer %}
         <!-- Footer-->
-        <footer id="footer" class="row pt-4 pb-3 mt-5" role="contentinfo">
+        <footer id="footer" class="row pt-4 pb-3 mt-auto" role="contentinfo">
             <div class="col-12">
                 <div class="row text-center gy-3">
                     <div class="col-12 col-md-4">
@@ -281,4 +281,4 @@
     </script>
     {% endcache %}
 </body>
-</html>
+</html>