Fix Swift 5.7 build errors

[rgoldberg]

Fixed all Swift 5.7 build breaks in main, namely:

• Package.swift: target array missing a comma
• ToolInfo.swift: contains 2 if expressions, which are not supported by Swift 5.7
• GenerateManual.swift: contains switch expression, which is not supported by Swift 5.7
• DumpHelpGenerationTests.swift: contains switch expression, which is not supported by Swift 5.7

Resolve #675

Checklist

• I've added at least one test that validates that my change is working, if appropriate
• I've followed the code style of the rest of the project
• I've read the Contribution Guidelines
• I've updated the documentation if necessary

[rauhul]

@swift-ci please test

[rauhul]

I'd love a follow up PR that drops the increases supported version of argument parser to one of 5.9, 5.10, or 6.0. I think 5.9 is most inline with other repos like swift-nio which try to support the last 3 minor releases of Swift.

[rgoldberg]

@rauhul Please don't drop support for 5.7 anytime soon. I am working on fixing many issues in completion script generation. The project for which I'm using SAP is mas, which still needs to support 5.7.

[rauhul]

@rauhul Please don't drop support for 5.7 anytime soon. I am working on fixing many issues in completion script generation. The project for which I'm using SAP is mas, which still needs to support 5.7.

Gotcha, what's preventing yall from updating to a newer toolchain?

[rgoldberg]

Some developers stuck on macOS 12 (therefore Xcode 14.2, therefore Swift 5.7) until M4 Mac Studio release.

I'd suggest supporting Swift back to the most recent EOL macOS (currently macOS 12, so Swift 5.7), to give people leeway to purchase the replacement machine they want when their Mac goes EOL.