[FIX] website: display the flag image of the language selector

Issue introduced by commit b0a2a41
The template's "flags" value was not in the t-nocache values to use when
rendering languages.

X-original-commit: 7827d2dbc1fbef3cc0dc898baa0af30ed1f23fca
Part-of: odoo/odoo#95222

addons/website/static/tests/tours/automatic_editor.js

@@ -48,6 +48,7 @@ wTourUtils.registerEditionTour('automatic_editor_on_new_website', {
     {
         content: "Select parseltongue",
         trigger: 'iframe a.js_change_lang[data-url_code=pa_GB]',
+        extra_trigger: 'iframe a.js_change_lang .o_lang_flag',
     },
     {
         content: "Check that we're on parseltongue and then go to settings",

addons/website/views/website_templates.xml

@@ -1886,6 +1886,10 @@
 </template>
 
 <template id="language_selector" inherit_id="portal.language_selector">
+    <xpath expr="//t[@t-nocache]" position="attributes">
+        <attribute name="t-nocache-flags">flags</attribute>
+    </xpath>
+
     <xpath expr="//t[@t-set='active_lang']" position="before">
         <t t-if="lang not in (lg[0] for lg in languages)">
             <t t-set="lang" t-value="website.default_lang_id.code"/>