Add redis support and disabled qwant by default.

Larger instances will benefit from this change massively.
Also QWant was spamming the logs with some chaptcha problem so best to disable it for now.

searxng/settings.yml

@@ -12,6 +12,9 @@ search:
 server:
   secret_key: 'a2fb23f1b02e6ee83875b09826990de0f6bd908b6638e8c10277d415f6ab852b' # Is overwritten by ${SEARXNG_SECRET}
 
+redis:
+  url: redis://redict:6379/0
+
 engines:
-  - name: wolframalpha
-    disabled: false
+  - name: qwant
+    disabled: true