[enh] network: add impersonate parameter

see
* https://github.com/lexiforest/curl_cffi
* https://github.com/vgavro/httpx-curl-cffi

searx/network/network.py

@@ -53,6 +53,7 @@ class Network:
         'max_redirects',
         'retries',
         'retry_on_http_error',
+        'impersonate',
         '_local_addresses_cycle',
         '_proxies_cycle',
         '_clients',
@@ -63,6 +64,7 @@ class Network:
 
     def __init__(
         # pylint: disable=too-many-arguments
+        # pylint: disable=too-many-positional-arguments
         self,
         enable_http=True,
         verify=True,
@@ -77,6 +79,7 @@ class Network:
         retry_on_http_error=None,
         max_redirects=30,
         logger_name=None,
+        impersonate=None,
     ):
 
         self.enable_http = enable_http
@@ -91,6 +94,7 @@ class Network:
         self.retries = retries
         self.retry_on_http_error = retry_on_http_error
         self.max_redirects = max_redirects
+        self.impersonate = impersonate
         self._local_addresses_cycle = self.get_ipaddress_cycle()
         self._proxies_cycle = self.get_proxy_cycles()
         self._clients = {}
@@ -185,10 +189,11 @@ class Network:
         max_redirects = self.max_redirects if max_redirects is None else max_redirects
         local_address = next(self._local_addresses_cycle)
         proxies = next(self._proxies_cycle)  # is a tuple so it can be part of the key
-        key = (verify, max_redirects, local_address, proxies)
+        key = (verify, max_redirects, local_address, proxies, self.impersonate)
         hook_log_response = self.log_response if sxng_debug else None
         if key not in self._clients or self._clients[key].is_closed:
             client = new_client(
+                self.impersonate,
                 self.enable_http,
                 verify,
                 self.enable_http2,