[mod] drop unused setting option brand:twitter_url

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

searx/__init__.py

@@ -96,9 +96,4 @@ class _brand_namespace:  # pylint: disable=invalid-name
     def WIKI_URL(self):
         return self.get_val('brand', 'wiki_url')
 
-    @property
-    def TWITTER_URL(self):
-        return self.get_val('brand', 'twitter_url')
-
-
 brand = _brand_namespace()

searx/settings_defaults.py

@@ -137,7 +137,6 @@ SCHEMA = {
         'docs_url': SettingsValue(str, None),
         'public_instances': SettingsValue(str, None),
         'wiki_url': SettingsValue(str, None),
-        'twitter_url': SettingsValue(str, None),
     },
     'search': {
         'safe_search': SettingsValue((0,1,2), 0),