Support Swift 5.6

[aroshipup]

Overview

• Added Swift 5.6 support to solve the problem of failing to generate mocks in Xcode 13.3

  Notes

• I have not added CI execution in Swift 5.6 because GitHub-hosted runners in github actions does not currently support macOS 12

[CLAassistant]

All committers have signed the CLA.

[EspressoCup]

@aroshipup thanks for the change; please use the tag as @yutailang0119 mentioned, thanks!

[aroshipup]

@EspressoCup Thanks, but SwiftSyntax release tag 0.50600.0 has the following problem and fails to install as a dependent package, so I suggest that once we get the current version ( .branch("release/5.6") ) in. https://bugs.swift.org/browse/SR-15989

error: the target 'SwiftSyntax' in product 'SwiftSyntax' contains unsafe build flags
error: the target 'SwiftSyntax' in product 'SwiftSyntaxParser' contains unsafe build flags

[EspressoCup]

@EspressoCup Thanks, but SwiftSyntax release tag 0.50600.0 has the following problem and fails to install as a dependent package, so I suggest that once we get the current version ( .branch("release/5.6") ) in. https://bugs.swift.org/browse/SR-15989

error: the target 'SwiftSyntax' in product 'SwiftSyntax' contains unsafe build flags
error: the target 'SwiftSyntax' in product 'SwiftSyntaxParser' contains unsafe build flags

I see; thanks for checking.

[aroshipup]

@EspressoCup Due to the recent release of a new version of swift-argument-parser, builds were failing in environments with versions below Xcode 13.3, as shown in the CI check results. Therefore, this problem has been resolved by setting the upper version limit of swift-argument-parser to 1.0.3. https://github.com/apple/swift-argument-parser/releases

https://github.com/uber/mockolo/pull/178/commits/f38ae33f3a43c4f7f104fe6c142c7c1aac9dd1a7