Accept URL as filename

[fisker]

const pool = new Tinypool({
-  filename: new URL('./worker.mjs', import.meta.url).href,
+  filename: new URL('./worker.mjs', import.meta.url),
})

1. Convenient to use
2. Align with Worker constructor

[AriPerkkio]

This should be doable, as child_process.fork() also supports it: https://nodejs.org/api/child_process.html#child_processforkmodulepath-args-options

Though we'll need to make sure it works on Windows too, as we've had URL issues there before.

[fisker]

I was thinking change

tinypool/src/index.ts

Line 304 in ec78ce9

this.filename = filename

to

this.filename = filename instanceof URL ? filename.href : filename

I don't think it related to Node.js API support