Bump autoprefixer from 9.7.5 to 9.8.6

Bumps [autoprefixer](https://github.com/postcss/autoprefixer) from 9.7.5 to 9.8.6.
- [Release notes](https://github.com/postcss/autoprefixer/releases)
- [Changelog](https://github.com/postcss/autoprefixer/blob/master/CHANGELOG.md)
- [Commits](postcss/autoprefixer@9.7.5...9.8.6)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Author: dependabot-preview[bot]