[fix] bing engines - geoblocking in China (#6134)

In regions like China, the domain must be adjusted to avoid a redirect.

- https://github.com/searxng/searxng/issues/5243
- https://github.com/searxng/searxng/pull/5324
- https://github.com/searxng/searxng/pull/6133

Suggested / tested by @hubutui in https://github.com/searxng/searxng/pull/6133#issuecomment-4534637069

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

searx/engines/bing_images.py

@@ -34,7 +34,7 @@ time_map = {
     "year": 60 * 24 * 365,
 }
 
-base_url = "https://www.bing.com/images/async"
+base_url = "https://www.bing.com"
 """Bing-Image search URL"""
 
 
@@ -64,9 +64,7 @@ def request(query, params):
     if params["time_range"]:
         query_params["qft"] = "filterui:age-lt%s" % time_map[params["time_range"]]
 
-    params["url"] = base_url + "?" + urlencode(query_params)
-
-    return params
+    params["url"] = base_url + "/images/async?" + urlencode(query_params)
 
 
 def response(resp):