Neovim: support Windows/osx neovim in tests on CI

[saidelike]

we need to support the latest version on all the operating systems so we need to add support for Windows and osx

From https://github.com/cursorless-dev/cursorless/issues/2367#issuecomment-2141738371

these are my tests so far

OS	neovim	node	Result
linux	stable	v18.20.2/v20.12.1	pass
osx	stable	v18.20.2/v20.12.1	neovim npm package not found
win	stable	v18.20.2/v20.12.1	config not found
linux	v0.10.0	v18.20.2/v20.12.1	pass
osx	v0.10.0	v18.20.2/v20.12.1	pass
win	v0.10.0	v18.20.2/v20.12.1	config not found
linux	v0.9.5	v18.20.2/v20.12.1	pass partially (some tests fail)
osx	v0.9.5	v18.20.2/v20.12.1	pass
win	v0.9.5	v18.20.2/v20.12.1	config not found