[FIX] odoo service: fix location of res_country_data.xml file

It has been moved inside base/data, instead of base/res.
We have to adapt code that is calling it.

odoo/service/db.py

@@ -405,7 +405,7 @@ def exp_list_lang():
 
 def exp_list_countries():
     list_countries = []
-    root = ET.parse(os.path.join(odoo.tools.config['root_path'], 'addons/base/res/res_country_data.xml')).getroot()
+    root = ET.parse(os.path.join(odoo.tools.config['root_path'], 'addons/base/data/res_country_data.xml')).getroot()
     for country in root.find('data').findall('record[@model="res.country"]'):
         name = country.find('field[@name="name"]').text
         code = country.find('field[@name="code"]').text