[fix] false is an invalid value for wiki_url in settings.yml (#5046)

Closes: https://github.com/searxng/searxng/issues/5045

searx/settings_defaults.py

@@ -150,7 +150,7 @@ SCHEMA = {
         'new_issue_url': SettingsValue(str, 'https://github.com/searxng/searxng/issues/new'),
         'docs_url': SettingsValue(str, 'https://docs.searxng.org'),
         'public_instances': SettingsValue((False, str), 'https://searx.space'),
-        'wiki_url': SettingsValue(str, 'https://github.com/searxng/searxng/wiki'),
+        'wiki_url': SettingsValue((False, str), 'https://github.com/searxng/searxng/wiki'),
         'custom': SettingsValue(dict, {'links': {}}),
     },
     'search': {