[FIX] web: darkmode switch display on small screen

This commit fixes the collapse between the User Menu's Dark Mode check
box and its label on small screen.

Follow-up of odoo/odoo@49176fe372 .

opw-3474193

closes odoo/odoo#133115

X-original-commit: 85ce415d756a454fb4c35588883cd23c1e7365a2
Related: odoo/enterprise#46268
Signed-off-by: Romeo Fragomeli (rfr) <rfr@odoo.com>
Signed-off-by: Pierre Paridans (app) <app@odoo.com>

addons/web/static/src/webclient/burger_menu/burger_user_menu/burger_user_menu.xml

@@ -9,7 +9,7 @@
               <CheckBox
                   t-if="element.type == 'switch'"
                   value="element.isChecked"
-                  className="'dropdown-item form-switch d-flex flex-row-reverse justify-content-between py-3 fs-4'"
+                  className="'dropdown-item form-switch d-flex flex-row-reverse justify-content-between py-3 fs-4 w-100'"
                   onChange="element.callback"
               >
                   <t t-out="element.description"/>