[mod] migrate from Redis to Valkey (#4795)

This patch migrates from `redis==5.2.1` [1] to `valkey==6.1.0` [2].

The migration to valkey is necessary because the company behind Redis has decided
to abandon the open source license. After experiencing a drop in user numbers,
they now want to run it under a dual license again. But this move demonstrates
once again how unreliable the company is and how it treats open source
developers.

To review first, read the docs::

    $ make docs.live

Follow the instructions to remove redis:

- http://0.0.0.0:8000/admin/settings/settings_redis.html

Config and install a local valkey DB:

- http://0.0.0.0:8000/admin/settings/settings_valkey.html

[1] https://pypi.org/project/redis/
[2] https://pypi.org/project/valkey/

Co-authored-by: HLFH <gaspard@dhautefeuille.eu>
Co-authored-by: Markus Heiser <markus.heiser@darmarit.de>

searx/botdetection/__init__.py

@@ -12,11 +12,11 @@ from ._helpers import too_many_requests
 
 __all__ = ['dump_request', 'get_network', 'get_real_ip', 'too_many_requests']
 
-redis_client = None
+valkey_client = None
 cfg = None
 
 
-def init(_cfg, _redis_client):
-    global redis_client, cfg  # pylint: disable=global-statement
-    redis_client = _redis_client
+def init(_cfg, _valkey_client):
+    global valkey_client, cfg  # pylint: disable=global-statement
+    valkey_client = _valkey_client
     cfg = _cfg