use default xcode version (#69)

azure-pipelines.yml

@@ -21,7 +21,5 @@ steps:
     sdk: 'iphoneos'
     xcWorkspacePath: '*.xcworkspace'
     scheme: 'sampleapp-ios-swift'
-    xcodeVersion: 'specifyPath'
-    xcodeDeveloperDir: '/Applications/Xcode_11.3.app'
     packageApp: false
     publishJUnitResults: true