Bump laravel/cashier from 13.8.3 to 13.8.4

Bumps [laravel/cashier](https://github.com/laravel/cashier-stripe) from 13.8.3 to 13.8.4.
- [Release notes](https://github.com/laravel/cashier-stripe/releases)
- [Changelog](https://github.com/laravel/cashier-stripe/blob/13.x/CHANGELOG.md)
- [Commits](laravel/cashier-stripe@v13.8.3...v13.8.4)

---
updated-dependencies:
- dependency-name: laravel/cashier
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]