make AppVeyor retry failed runs.
make AppVeyor retry failed runs.

Tests are just too brittle on AppVeyor. `npm install` fails frequently,
and Node on Windows does not seem to reliably flush stdout/stderr
of forked child processes.

I don't like this, but I'm at a loss for other solutions.

vdemedes/ava,andywer/ava-ts,avajs/ava,Collinslenjo/ava,BarryThePenguin/ava,andywer/ava-ts,avajs/ava,floatdrop/ava,Collinslenjo/ava,sindresorhus/ava