[FIX] web: reduce spacing between toast notifications

Currently, toast notifications are too far apart with each other if there are
multiple notifications.

So with this commit, we have reduced the margin from the bottom so it looks
closer.

Task : 2278730

closes odoo/odoo#53381

X-original-commit: d43008b38b7b71a5dc1a260560a98ca75e1fafb4
Signed-off-by: Aaron Bohy (aab) <aab@odoo.com>

addons/web/static/src/scss/notification.scss

@@ -7,6 +7,9 @@
     margin-right: 8px;
     max-width: 100%;
 
+    .toast:not(:last-child) {
+        margin-bottom: 5px;
+    }
     .o_notification {
         width: 100%;