fix: avoid using fs/promises

[benmccann]

It might be less reliable since it's newer? (example: https://github.com/nodejs/node/issues/51031)

People are reporting weird errors (https://github.com/sveltejs/kit/discussions/11098) and this is my best guess at the moment

[changeset-bot[bot]]

🦋 Changeset detected

Latest commit: 86967b94f5996721c34208a7a78ec09e5188f3b9

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

| Name | Type | | --------------- | ----- | | vite-imagetools | Patch |

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[codecov[bot]]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (0df85ac) 93.60% compared to head (86967b9) 93.60%.

Files	Patch %	Lines
packages/vite/src/utils.ts	50.00%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #675 +/- ## ======================================= Coverage 93.60% 93.60% ======================================= Files 32 32 Lines 1189 1189 Branches 189 189 ======================================= Hits 1113 1113 Misses 76 76 ``` | [Flag](https://app.codecov.io/gh/JonasKruckenberg/imagetools/pull/675/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Jonas+Kruckenberg) | Coverage Δ | | |---|---|---| | [imagetools-core](https://app.codecov.io/gh/JonasKruckenberg/imagetools/pull/675/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Jonas+Kruckenberg) | `97.01% <ø> (ø)` | | | [vite-imagetools](https://app.codecov.io/gh/JonasKruckenberg/imagetools/pull/675/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Jonas+Kruckenberg) | `78.44% <50.00%> (ø)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Jonas+Kruckenberg#carryforward-flags-in-the-pull-request-comment) to find out more.

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