Pass different parameters to mktemp on OSX

[mlopes]

No description provided.

[mlopes]

Fixes #3

[nwinkler]

Any updates on getting this merged, @ztombol?

[jsok]

Wouldn't you want to detect which mktemp rather than the OS?

if mktemp --version >/dev/null 2>&1 ; then
    echo Using GNU mktemp
else
    echo Using BSD mktemp
fi

[mlopes]

Feel free to add my remote and implement that change, I currently don't have bats set up on my machine, and given that this PR is been ignored for about 3 months now, I don't think it's worth the effort to try to improve it.

[retr0h]

I've verified this works as expected on my mac.

[retr0h]

Given mac doesn't work at all, could we land this rather than bike shed it?

[peshay]

@mlopes since it seems this repo is not longer maintained, I started my own fork and working on some changes there: https://github.com/peshay/bats-file/tree/patch-1
I'll also integrate your suggestion from here to use mktemp -d -- "${BATS_TMPDIR}${template}" 2>&1 but I make no difference for Darwin OS or not, because it works for all systems.
Actually still 3 tests fail for me on macOS and I need to further investigate