tests: Use .errno instead of .args[0] for OSError exceptions.

Signed-off-by: Damien George <damien@micropython.org>

tests/extmod/usocket_tcp_basic.py

@@ -14,4 +14,4 @@ s = socket.socket()
 try:
     s.recv(1)
 except OSError as er:
-    print("ENOTCONN:", er.args[0] == errno.ENOTCONN)
+    print("ENOTCONN:", er.errno == errno.ENOTCONN)