bpo-31870: Fix test_get_server_certificate_timeout on Windows (GH-25570)

Some OS do not support millisecond granularity in select(). Use 100ms
timeout and a server callback with sleep to emulate a slow server.

Author: tiran

Lib/test/test_ssl.py

@@ -2137,9 +2137,13 @@ def test_get_server_certificate_fail(self):
         _test_get_server_certificate_fail(self, *self.server_addr)
 
     def test_get_server_certificate_timeout(self):
+        def servername_cb(ssl_sock, server_name, initial_context):
+            time.sleep(0.2)
+        self.server_context.set_servername_callback(servername_cb)
+
         with self.assertRaises(socket.timeout):
             ssl.get_server_certificate(self.server_addr, ca_certs=SIGNING_CA,
-                                       timeout=0.0001)
+                                       timeout=0.1)
 
     def test_ciphers(self):
         with test_wrap_socket(socket.socket(socket.AF_INET),