Get tests passing on GitHub Actions Windows runners

[mortenpi]

There are some weird, probably newline-related issues that fail the tests when (in test/doctests) running them on the windows-latest runners of GitHub Actions. I am unable to reproduce them locally on a Windows machine and AppVeyor works fine.

So because of that in #1496 I stuck with AppVeyor for Windows testing. But ideally we'd like to get the tests working reliably also on GitHub Actions. If anyone wants to take a look at this, I have some commits on the mp/gha-actions branch where I tried out a few things with partial success.

[fredrikekre]

Might be useful to try https://github.com/marketplace/actions/debugging-with-tmate to get ssh access to the machine.

[odow]

This sounds familiar: https://github.com/odow/SDDP.jl/blob/95e4a7fa9ed2e7ec91280abc7ceb793c23fc4b36/docs/make.jl#L20-L27
Before calling :fix, I had to rewrite the line endings. I don't have a Windows machine, but Morten, if you can't reproduce you probably autocrlf enabled. Or GH actions has it set differently.

[mortenpi]

if you can't reproduce you probably autocrlf enabled

Yeah, I think you're right that this is the culprit. As far as I can tell:

• AppVeyor sets core.autocrlf = input, so the checked out files have LF, and so the tests were passing.
• GHA sets core.autocrlf = true, so the checked out files have CRLF.
• On the Windows VM where I tried to repro it.. it appears that core.autocrlf = true globally, but when I manually checked the files, they have been checked out with LF (:man_shrugging:; I think I did pkg> dev so maybe because of that). So it makes sense that the tests would pass, like on AppVeyor.