Increase timeout for STUN server to start, to fix flaky tests

Author: zpostfacto

tests/test_p2p.py

@@ -20,7 +20,7 @@
 g_server_ready = threading.Event()
 g_stun_ready = threading.Event()
 g_turn_lan_ready = threading.Event()
-g_server_startup_timeout = 3  # seconds
+g_server_startup_timeout = 30  # seconds.  Generous, because cold-starting a second Python interpreter on a Windows CI runner can take several seconds.
 g_spew_level = None
 g_p2p_rendezvous_level = None
 g_stun_ip = "127.0.100.1"