Revert #185: Bump minimum platform version to 10.13

[artemcm]

It was merged prematurely and is causing breaks in other projects (SwiftPM and, cascadingly, everything that relies on it).

[artemcm]

@swift-ci please test

[DougGregor]

Sorry about the premature merge :(

[artemcm]

Sorry about the premature merge :(

No worries!

@sstadelman, please re-create the original PR and merge together with the corresponding components in SwiftPM and TSCLib.
Our CI bots have some capabilities to do cross-repository testing, if that is necessary:
https://github.com/apple/swift/blob/master/docs/ContinuousIntegration.md#cross-repository-testing

[sstadelman]

@artemcm By 'merge together with corresponding components' I think you mean test like here?

[artemcm]

@artemcm By 'merge together with corresponding components' I think you mean test like here?

For cross-repository-testing, yes, exactly like that.
But I don't know of a good mechanism in place for actual simultaneous merging after testing succeeds, though.
So it will probably have to consist of clicking multiple green buttons as "simultaneously" as possible. 😬