Missing files using `c8 report` on windows

I'm observing that we are ignoring certain files from the coverage report on windows due to a quirk in the way [test-exclude](https://github.com/istanbuljs/test-exclude) works.

When we get here on windows: https://github.com/bcoe/c8/blob/master/lib/report.js#L253

We end up at this block in include/exclude: https://github.com/istanbuljs/test-exclude/blob/master/is-outside-dir-win32.js#L9 (which is for win32)

This code is sensitive to case. :( The fix will need to go there, but I need to get an approval before I can PR.

But in summary, given the case of paths like dir/filename: `D:\dev\some\long` / `d:\dev\some\long\path\to\my.js` this code:

`return !minimatch(path.resolve(dir, filename), path.join(dir, '**'), dot);`

Will return true, incorrectly indicating that the file is outside our cwd, Whereas including `nocase` in the options (supplied as dot) will correctly return false.