[mod] upgrade requests to version 2.24.0. use ssl instead of pyopenssl.

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.

searx/__init__.py

@@ -15,12 +15,10 @@ along with searx. If not, see < http://www.gnu.org/licenses/ >.
 (C) 2013- by Adam Tauber, <asciimoo@gmail.com>
 '''
 
-import certifi
 import logging
 from os import environ
 from os.path import realpath, dirname, join, abspath, isfile
 from io import open
-from ssl import OPENSSL_VERSION_INFO, OPENSSL_VERSION
 from yaml import safe_load
 
 
@@ -81,13 +79,6 @@ else:
 
 logger = logging.getLogger('searx')
 logger.debug('read configuration from %s', settings_path)
-# Workaround for openssl versions <1.0.2
-# https://github.com/certifi/python-certifi/issues/26
-if OPENSSL_VERSION_INFO[0:3] < (1, 0, 2):
-    if hasattr(certifi, 'old_where'):
-        environ['REQUESTS_CA_BUNDLE'] = certifi.old_where()
-    logger.warning('You are using an old openssl version({0}), please upgrade above 1.0.2!'.format(OPENSSL_VERSION))
-
 logger.info('Initialisation done')
 
 if 'SEARX_SECRET' in environ: