update package to swift 5

[mshehan]

TL;DR

Update Swift Package Manager configuration to Swift 5.0 and fix compatibility issues.

What changed?

• Updated Swift tools version from 4.2 to 5.0
• Added platform requirements (iOS 12+, tvOS 12+, macOS 10.13+)
• Added test target to Package.swift
• Fixed Swift 5 compatibility issues:
  • Added @retroactive to Equatable conformance
  • Updated string index handling from encodedOffset to utf16Offset
  • Updated Transport initializer parameter naming for readability

How to test?

1. Build the package with Swift 5.0 or newer
2. Run the test suite to verify all tests pass
3. Verify the library works correctly on iOS 12+, tvOS 12+, and macOS 10.13+

Why make this change?

Swift 5.0 introduced ABI stability and several language changes that required updates to the codebase. This change ensures compatibility with modern Swift versions while maintaining support for specific platform versions. The addition of the test target in Package.swift also improves the development experience by making tests directly accessible through SPM.

[mshehan]

• update package to swift 5 #114 👈 (View in Graphite)
• master

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