[FIX] base: Invalid flag image url computed for Serbian lang sr@latin

When computing flag_image_url field on res.lang model an invalid url is generated due to the peculiar format for serbian lang code sr@latin which has "@" sign instead of expected "_" sign and thus the unexisting url is computed, so we are forced to populate binary field flag_image instead.

Part-of: odoo#113490

Author: pnajman-modoolar

odoo/addons/base/data/res_lang_data.xml

@@ -10,5 +10,8 @@
         <record id="base.lang_ar" model="res.lang">
             <field name="flag_image" type="base64" file="base/static/img/lang_flags/lang_ar.png"/>
         </record>
+        <record id="base.lang_sr@latin" model="res.lang">
+            <field name="flag_image" type="base64" file="base/static/img/country_flags/rs.png"/>
+        </record>
     </data>
 </odoo>