Swift 5.5 and Linux Unit tests

[mikolasstuchlik]

Recently, it has come to my attention, that swift test no longer needs, nor allows the LinuxMain.swift file in the Tests/ directory.

futuredapp/FTAPIKit@3feab35

Using #if swift(>=5.5) && !os(Linux) statement in the LinuxMain.swift won't work, the compilation (or linking) will fail as long as the LinuxMain.swift file is present.

I suppose this is a bug in the SPM itself, since the SPM should ignore all files that are outside of the target structure.

This bug is relevant on Swift 5.5. Since the minimal compiler version of this package is Swift 5.4, I suggest taking no action at this time, since deleting the LinuxMain.swift file will break the tests on Swift 5.4.