Replace piscina with tinypool

[fisker]

Fixes #59

[fisker]

Need update https://github.com/babel/babel/blob/7c29fbc4db7809d24789235b0597e7e8dd61c4ae/packages/babel-core/test/errors-stacks.js#L30

[nicolo-ribaudo]

Do you have any before/after for how long this takes to run Prettier's tests?

[fisker]

Since Prettier tests runs with --runInBand, so there is nothing to compare at all. I'll make it work for --maxWorkers first.

[fisker]

Here is the result:

With piscina (1m 27s)

https://github.com/nicolo-ribaudo/jest-light-runner/actions/runs/7013294881/job/19079198358?pr=82

With tinypool (1m 28s)

https://github.com/nicolo-ribaudo/jest-light-runner/actions/runs/7013320207/job/19079264994?pr=82

[nicolo-ribaudo]

Given that this does introduce perf regressions, I'm accepting the change given that it reduces the number of deps.

[nicolo-ribaudo]

Let me know if this is ready to merge, then I'll update the Babel tests :)

[fisker]

I think it's ready.