Downgrade server security level in security level test

We want to test the client side error here, so make sure the
server side can start up successfully.

ext/openssl/tests/stream_security_level.phpt

@@ -21,7 +21,10 @@ $serverCode = <<<'CODE'
 	$serverUri = "ssl://127.0.0.1:64322";
 	$serverFlags = STREAM_SERVER_BIND | STREAM_SERVER_LISTEN;
 	$serverCtx = stream_context_create(['ssl' => [
-		'local_cert' => '%s'
+		'local_cert' => '%s',
+		// Make sure the server side starts up successfully if the default security level is
+		// higher. We want to test the error at the client side.
+		'security_level' => 1,
 	]]);
 
 	$server = stream_socket_server($serverUri, $errno, $errstr, $serverFlags, $serverCtx);