Incorrect name of SPM package

I've added a SPM package dependency called `JWTDecode.swift`. In Xcode it appears as `JWTDecode` and that's what is set in the project.

However, if I change anything in the project (i.e. add/delete file) using Xcodeproj, the newly saved file adds a `.swift` suffix to the package name.

I guess it should be consistent with Xcode, otherwise opening the project removes `.swift` and using Xcodeproj brings `.swift` back :). I tested it with Xcode 15.3.

Reproduce the package-name change in Xcodeproj with the `JWTDecode.swift` dependency and Xcode 15.3, then inspect how the project serializes Swift package dependencies when saving. Done means saving a project with Xcodeproj preserves the package name as `JWTDecode`, without adding the `.swift` suffix.

Written by the indexing model from the issue text.