enhance: simplify the structure of search_params

Signed-off-by: lixinguo <[email protected]>

pymilvus/client/prepare.py

@@ -978,7 +978,15 @@ def search_requests_with_expr(
 
         if param.get(HINTS) is not None:
             search_params[HINTS] = param[HINTS]
-
+
+        # after 2.5.1, all parameters of search_params can be written into one layer 
+        # no more parameters will be written searchParams.params
+        # to ensure compatibility and milvus can still get a json format parameter
+        # try to write all the parameters under searchParams into searchParams.Params
+        for key, value in search_params.items():
+            if key != "params":
+                params[key] = value
+
         req_params = [
             common_types.KeyValuePair(key=str(key), value=utils.dumps(value))
             for key, value in search_params.items()