Bump conf from 12.0.0 to 15.0.2

Bumps [conf](https://github.com/sindresorhus/conf) from 12.0.0 to 15.0.2.
- [Release notes](https://github.com/sindresorhus/conf/releases)
- [Commits](sindresorhus/conf@v12.0.0...v15.0.2)

---
updated-dependencies:
- dependency-name: conf
  dependency-version: 15.0.2
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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Author: dependabot[bot]