ci: bump to Xcode 11.4 and iOS 13.4 (#257)

Author: KazuCocoa

ci-jobs/functional_test.yml

@@ -2,8 +2,8 @@
 parameters:
   vmImage: 'macOS-10.15'
   vmImageForIOS: 'macOS-10.15' # Not sure the reason, but macOS 10.14 instance raises no info.plist error
-  xcodeForIOS: 11.3
-  xcodeForTVOS: 11.3
+  xcodeForIOS: 11.4
+  xcodeForTVOS: 11.4
   androidSDK: 29
   appiumVersion: 'beta'
   ignoreVersionSkip: true

test/test_helper.rb

@@ -103,7 +103,7 @@ def self.windows
 
     # Require a simulator which OS version is 11.4, for example.
     def ios(platform_name = :ios)
-      platform_version = '13.3'
+      platform_version = '13.4'
       wda_port = wda_local_port
 
       real_device = ENV['REAL'] ? true : false