Upgrade Sauce Labs Appium version (#518)

Author: chasenlehara

test.sauce-labs.js

@@ -8,7 +8,7 @@ testSauceLabs({
 		platform: 'Windows 10'
 	}, {
 		browserName: 'Safari',
-		'appium-version': '1.7.1',
+		'appium-version': '1.9.1',
 		platformName: 'iOS',
 		platformVersion: '11.0',
 		deviceName: 'iPhone 8 Simulator'