Bump gulp-autoprefixer from 9.0.0 to 10.0.0

Bumps [gulp-autoprefixer](https://github.com/sindresorhus/gulp-autoprefixer) from 9.0.0 to 10.0.0.
- [Release notes](https://github.com/sindresorhus/gulp-autoprefixer/releases)
- [Commits](sindresorhus/gulp-autoprefixer@v9.0.0...v10.0.0)

---
updated-dependencies:
- dependency-name: gulp-autoprefixer
  dependency-version: 10.0.0
  dependency-type: direct:development
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]