Issues with the xcodeproj file

[jasdeepsaini]

I have a PR that fixes several issues with CombineEXT.xcodeproj. I forked the project to investigate a bug with CurrentValueRelay and could not run tests until I made these changes. Tests do run fine from the command line.

Fixes to get the project and tests to build:

• Deleted the missing MapTo and MapToTests files.
• Changed the deployment target to iOS 13 to match the minimum target of the Package file.
• Updated the CombineSchedulers package to 0.5.3 to match the Package file.
• The Package.resolved file automatically got updated to v2 since I am using Xcode 13.

Project cleanup

• Deleted the missing Carthage and CHANGELOG.MD files.

Missing library and test files added to the project:

• MapToValue.swift
• MapToValueTests.swift
• MapToResult.swift
• MapToResultTests.swift
• Enumerated.swift
• EnumeratedTests.swift

[freak4pc]

Hey, there's no need to open an issue in addition to the PR. Let's keep a discussion there.
Thanks.