[fix] typo in get_engine_locale

Due to a typo in get_engine_locale, a language selection like `!qw :de siemens`
did not work.

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

searx/locales.py

@@ -217,7 +217,7 @@ def get_engine_locale(searxng_locale, engine_locales, default=None):
         locale = babel.Locale.parse(searxng_locale, sep='-')
     except babel.core.UnknownLocaleError:
         try:
-            locale = babel.Locale.parse(searxng_locale.split('-')[1])
+            locale = babel.Locale.parse(searxng_locale.split('-')[0])
         except babel.core.UnknownLocaleError:
             return default