Add destroy method for graceful shutdown of worker pool

[cdm6a]

I'm experiencing the following issue when running e2e tests using Jest:

Jest has detected the following 1 open handle potentially keeping Jest from exiting:

  ●  Piscina

    > 39 | import { transform } from 'camaro';
         | ^

      at new EventEmitterReferencingAsyncResource (node_modules/eventemitter-asyncresource/src/index.ts:23:5)
      at new EventEmitterAsyncResource (node_modules/eventemitter-asyncresource/src/index.ts:46:7)
      at new Piscina (node_modules/piscina/src/index.ts:893:5)
      at Object.<anonymous> (node_modules/camaro/index.js:13:12)

It appears a number of other folks may be running into this issue as well:

• piscina with jest piscinajs/piscina#83
• Memory allocation error #113 (comment)

The goal of this PR is to provide a way to shutdown the worker pool in the event someone may be running into this.

[tuananh]

Thanks. Will cut a release soon.

[cdm6a]

Hey @tuananh, did you happen to cut a release / publish this?

[tuananh]

Hey @tuananh, did you happen to cut a release / publish this?

I've published 6.2.2 to include this change https://www.npmjs.com/package/camaro?activeTab=versions