Upgrade xcode version for CI

[ghost]

This is experimental.

PR Checklist

• The PR title follows our guidelines: https://github.com/NativeScript/NativeScript/blob/master/CONTRIBUTING.md#commit-messages.
• There is an issue for the bug/feature this PR is for. To avoid wasting your time, it's best to open a suggestion issue first and wait for approval before working on it.
• All existing tests are passing
• Tests for the changes are included

What is the current behavior?

Travis CI iOS builds failing.

What is the new behavior?

Attempting to upgrade xcode version in hopes it will remedy the problem.

Fixes/Implements/Closes #[Issue Number].
N/A

@jdnichollsc

[ghost]

@jdnichollsc not sure if this is the desired solution but CI has passed. This tells me either a recent change is no longer compatible with xcode11.2, which I doubt, or Travis CI is either caching something or has changed their xcode11.2 image.

[jcassidyav]

If you are using the new native script 7 cli it is not compatible with Xcode 11.

https://nativescript.org/blog/nativescript-6-7-xcode-compatibility/

[jdnichollsc]

If you are using the new native script 7 cli it is not compatible with Xcode 11.

nativescript.org/blog/nativescript-6-7-xcode-compatibility

Ohh very interesting, thanks for sharing!

@jdnichollsc not sure if this is the desired solution but CI has passed. This tells me either a recent change is no longer compatible with xcode11.2, which I doubt, or Travis CI is either caching something or has changed their xcode11.2 image.

Thanks for your amazing help!