fix(dev): ensure vite-node doesn't load PostCSS config

[markdalgleish]

Fixes #12472.

tl;dr: Adding css: { postcss: {} } to our vite-node config is the equivalent of configFile: false but for PostCSS config files.

[changeset-bot]

🦋 Changeset detected

Latest commit: 9436650

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

This PR includes changesets to release 11 packages

Name	Type
@react-router/dev	Patch
@react-router/fs-routes	Patch
@react-router/remix-routes-option-adapter	Patch
create-react-router	Patch
react-router	Patch
react-router-dom	Patch
@react-router/architect	Patch
@react-router/cloudflare	Patch
@react-router/express	Patch
@react-router/node	Patch
@react-router/serve	Patch

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[github-actions]

🤖 Hello there,

We just published version 7.6.0 which includes this pull request. If you'd like to take it for a test run please try it out and let us know what you think!

Thanks!

[github-actions]

🤖 Hello there,

We just published version 7.6.1 which includes this pull request. If you'd like to take it for a test run please try it out and let us know what you think!

Thanks!