fix unzippedArchive path when searching for psd1 file

[joshschmitter]

Two changes:

• on non-unix platforms, fixed the psd1 file search
  • join-path on line 87 was joining two full paths, which is not a valid result.
  • I'm curious if this code path ever worked before. Is there something different about the test environment? I'm running windows 10, pwsh v7.
• allow the module to be in a repo subdirectory
  • This would only be a breaking change if there could be module dependencies in a parent directory above the module root, which I don't think is possible. It also wouldn't support nested modules, but I don't think those are supported by InstallModuleFromGitHub anyways.

[rennerom]

Catching up from issue #28. I feel like this worked on windows when I opened my last PR, but having limited access to windows machines at the time, it’s entirely possible I’m misremembering. I was also running windows 10 on ps 5.1 and using a forked version of this repo to work with ps 5.1, so definitely not the best q/a environment.

This change however appears to run just fine on my current windows 10 machine with ps7.

[jonaskuske]

I'm on PowerShell 7.3 / Win10 and the fix in this PR worked for me 👋