[IMP] web: show avatar correctly even when rectangle image is used

Before this commit,
In top-right corner, the avatar that is being shown doesn't correctly
look like a circle if the shape of the avatar is rectangle.

After this commit,
The avatar appears in the top-right corner will be shown in correct circle
shape, irrelevant of the image is square or not.

task-2042276
closes: #35265

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

addons/web/static/src/scss/navbar.scss

@@ -159,7 +159,9 @@ body.o_is_superuser .o_menu_systray {
         }
 
         .oe_topbar_avatar {
-            height: 17px;
+            height: 26px;
+            width: 26px;
+            object-fit: cover;
             transform: translateY(-2px);
         }
     }