[fix] add missing territory (country) name

Related-to: https://github.com/searxng/searxng/pull/1029#issuecomment-1086824911
Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

tests/unit/test_query.py

@@ -130,7 +130,7 @@ class TestLanguageParser(SearxTestCase):
         self.assertEqual(query.autocomplete_list, [":hu-hu"])
 
         query = RawTextQuery(':v', [])
-        self.assertEqual(query.autocomplete_list, [":vi", ":tiếng việt"])
+        self.assertEqual(query.autocomplete_list, [':vi', ':tiếng việt', ':việt_nam'])
 
 
 class TestTimeoutParser(SearxTestCase):