The duckduckgo engine requires an additional request after the results have been sent.
This commit makes sure that the second request uses the same HTTPAdapter
= the same IP address, and the same proxy.
check HTTP response:
* detect some comme CAPTCHA challenge (no solving). In this case the engine is suspended for long a time.
* otherwise raise HTTPError as before
the check is done in poolrequests.py (was before in search.py).
update qwant, wikipedia, wikidata to use raise_for_httperror instead of raise_for_status
requests 2.24.0 uses the ssl module except if it doesn't support SNI, in this case searx fallbacks to pyopenssl.
searx logs a critical message and exit if the ssl modules doesn't support SNI and pyOpenSSL is not installed.
searx logs a critical message and exit if the ssl version is older than 1.0.2.
in requirements.txt, pyopenssl is still required to install searx as a fallback.
