Update the swift-argument-parser to 1.2.3

[compnerd]

Pull Request Description

Update swift-argument-parser to 1.2.3.

Acceptance Criteria

To be accepted into the Swift source compatibility test suite, a project must:

• [ ] be an Xcode or swift package manager project
• [ ] support building on either Linux or macOS
• [ ] target Linux, macOS, or iOS/tvOS/watchOS device
• [ ] be contained in a publicly accessible git repository
• [ ] maintain a project branch that builds against Swift 4.0 and passes any unit tests
• [ ] have maintainers who will commit to resolve issues in a timely manner
• [ ] be compatible with the latest GM/Beta versions of Xcode and swiftpm
• [ ] add value not already included in the suite
• [ ] be licensed with one of the following permissive licenses:
  • BSD
  • MIT
  • Apache License, version 2.0
  • Eclipse Public License
  • Mozilla Public License (MPL) 1.1
  • MPL 2.0
  • CDDL
• [ ] pass ./project_precommit_check script run

Ensure project meets all listed requirements before submitting a pull request.

[shahmishal]

@swift-ci test