Xcode: Update default Swift language version for Xcode 10.2
Xcode 10.2 no longer supports Swift language versions before 4.0.
Fixes: #18871 (closed)
GitLab update will be applied on June 28th, between 8am and 10:30am, EDT (UTC-04:00). This site may have intermittent delays during that time.
Xcode 10.2 no longer supports Swift language versions before 4.0.
Fixes: #18871 (closed)