fix: crash with odd cpu counts

[yamazaki-sensei]

if os.cpu().length returns odd number, vitest crashes like this:

⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯ Unhandled Error ⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯
RangeError: Invalid array length
 ❯ new ThreadPool node_modules/tinypool/dist/esm/index.js:467:30
 ❯ new Tinypool node_modules/tinypool/dist/esm/index.js:739:31
 ❯ createPool node_modules/vitest/dist/chunk-vite-node-externalize.1efbe319.mjs:7057:16
 ❯ node_modules/vitest/dist/chunk-vite-node-externalize.1efbe319.mjs:10406:21
 ❯ Vitest.runFiles node_modules/vitest/dist/chunk-vite-node-externalize.1efbe319.mjs:10422:7
 ❯ Vitest.start node_modules/vitest/dist/chunk-vite-node-externalize.1efbe319.mjs:10349:5
 ❯ startVitest node_modules/vitest/dist/chunk-vite-node-externalize.1efbe319.mjs:11095:5
 ❯ CAC.start node_modules/vitest/dist/cli.mjs:667:9

This PR fixes this error.

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[sheremet-va]

By odd you mean float? I don't see why 3 is invalid array number 😄

[sheremet-va]

By odd you mean float? I don't see why 3 is invalid array number 😄

Ah, I see you mean CPU, and not the result 😄