chore(deps): update postcss-load-config to v6

[brc-dd]

Description

Bump postcss-load-config to v5. It added support for ESM + TS postcss configs (postcss/postcss-load-config#249). closes #15234 (and other issues that were closed/locked as they were upstream issues).

Additional context

It now needs jiti instead of ts-node for TS config files in Node.js. Might be a slightly breaking change for users?

---

What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

Before submitting the PR, please make sure you do the following

• Read the Contributing Guidelines, especially the Pull Request Guidelines.
• Check that there isn't already a PR that solves the problem the same way to avoid creating a duplicate.
• Provide a description in this PR that addresses what the PR is solving, or reference the issue that it solves (e.g. fixes #123).
• Update the corresponding documentation if needed.
• Ideally, include relevant tests that fail without this PR but pass with it.

[stackblitz]

Run & review this pull request in StackBlitz Codeflow.

[bluwy]

Yeah I think this is a breaking change and we can't bump this until v6. Unless we can still get ts-node working partially, but it doesn't seem likely now with postcss-load-config cutting a major.

Also for future reference, the renovate PR: #15234

[kuchta]

Hi guys,

Is there something blocking this PR to be part of final 6.0?

[patak-dev]

@kuchta the PR is already in the v6 milestone. Would you comment on your use case so your comment gives value to this PR?

[kuchta]

@patak-dev Well, it's not part of the v6 alpha release, so I'm curious... My use case is using postcss.config.ts

[patak-dev]

@kuchta I see. We're going to use the v6 alpha series to let the ecosystem test the Environment API branch. See:

• Environment API #16358

[ArnaudBarre]

For information I sent this PR to reduce bundle size: postcss/postcss-load-config#261