TODO: re-enable CI on Windows

[DilumAluthge]

The CI jobs on Windows are taking much longer than the Linux and macOS jobs. So I have disabled the Windows jobs for now.

Perhaps it's the specific CPUs that the Windows jobs are running on?

Maybe we could detect those CPUs, and run the tests with smaller matrices on those CPUs?

[DilumAluthge]

Or maybe Windows itself is the problem, in which case we could (in the test suite) detect if it is Windows, and then run the tests with smaller matrices if we are on Windows.

[chriselrod]

Currently, the matrices are 2x the size of Octavian.block_size. Only slightly larger would be fine.

Is it Windows, or maybe the computers running it just happen to be old?
If we're not measuring code coverage (which it sounds like we're not), I don't see why Windows should be any slower than another OS.

[DilumAluthge]

Let's run the jobs and see what the runtimes and CPUs are for the Windows jobs.

#23