add swift 4.2 builds to the CI

[quanvo87]

Description

Motivation and Context

How Has This Been Tested?

Checklist:

• [ ] I have submitted a CLA form
• [ ] If applicable, I have updated the documentation accordingly.
• [ ] If applicable, I have added tests to cover my changes.

[quanvo87]

@pushkarnk There is a build failure on macOS Swift dev snapshot: https://travis-ci.org/IBM-Swift/Swift-SMTP/jobs/402248095 Looks like a problem with https://github.com/IBM-Swift/CommonCrypto, do you know what this means?

[KyeMaloy97]

@quanvo87 hello, as it relies on CommonCrypto, we can't test on a Swift 4.2 snapshot until we have an Xcode 10 beta build. For now, can you comment out the Swift 4.2 tests and just update for Swift 4.1.2? Thank you :)

[quanvo87]

@KyeMaloy97 Hello, sorry, by comment out the 4.2 tests, do you mean actual unit tests or point the .travis.yml to 4.1.2 builds?

[KyeMaloy97]

@quanvo87 Just comment out the 4.2 builds in the travis.yml, we can uncomment the code when we have the available Xcode image

[CLAassistant]

Thank you for your submission, we really appreciate it. Like many open source projects, we ask that you all sign our Contributor License Agreement before we can accept your contribution.
1 out of 2 committers have signed the CLA.

:white_check_mark: pushkarnk
:x: quanvo87
_{You have signed the CLA already but the status is still pending? Let us recheck it.}

[quanvo87]

@KyeMaloy97 Does this look good?

[KyeMaloy97]

@quanvo87 almost, so we basically need a 4.0.3, 4.1.2 and 4.2 build for Linux, and a 4.0.3 and 4.1.2 build for macOS. The 4.2 build will have to wait until we have the Xcode 10 image for Travis.

To speed up the macOS builds, make sure the 4.0.3 build is using Xcode 9.2 and the 4.1.2 build is using Xcode 9.4, as these Xcode versions come with their respective Swift versions so theres no download required 😄 Thank you!

[quanvo87]

@KyeMaloy97 What about now?

[KyeMaloy97]

@quanvo87 looking good! Can you make sure you sign the CLA and we can merge this in, there should be a link in the required checks box 🙂

[quanvo87]

@KyeMaloy97 I believe I've signed it but the UI seems to not be updating. I'll go ahead and merge. Thanks for your help!