fix: change import to use type import for buildConfig from 'payload'

[y4aniv]

What?

Updated the import statement for buildConfig from import { buildConfig } from 'payload' to import type { buildConfig } from 'payload' to properly handle TypeScript types.

Why?

This change ensures that TypeScript properly treats buildConfig as a type rather than a runtime import, following project conventions and ensuring consistency with the rest of the documentation and code.

[AlessioGr]

buildConfig is a function that we call during runtime and is not just used as a type here. We can't strip it out when we compile the project

[AlessioGr]

Adding type to the GlobalConfig imports is good though - if you remove the buildConfig change, this should be fine