[hotfix] interim fix to get docker-build of CI without issues

There is an issue with redis v4.1.0 [1] / for the interim lets remove this
python dependency.

[1] https://github.com/searxng/searxng/issues/741

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

requirements.txt

@@ -13,4 +13,3 @@ uvloop==0.16.0
 httpx-socks[asyncio]==0.7.2
 langdetect==1.0.9
 setproctitle==1.2.2
-redis==4.1.0

searx/shared/redisdb.py

@@ -20,7 +20,6 @@ A redis DB connect can be tested by::
 """
 
 import logging
-import redis
 from searx import get_setting
 
 logger = logging.getLogger('searx.shared.redis')
@@ -29,6 +28,8 @@ _client = None
 
 def client():
     global _client  # pylint: disable=global-statement
+    import redis  # pylint: disable=import-error, import-outside-toplevel
+
     if _client is None:
         # not thread safe: in the worst case scenario, two or more clients are
         # initialized only one is kept, the others are garbage collected.
@@ -37,6 +38,8 @@ def client():
 
 
 def init():
+    import redis  # pylint: disable=import-error, import-outside-toplevel
+
     try:
         c = client()
         logger.info("connected redis DB --> %s", c.acl_whoami())