Update laminas/laminas-diactoros requirement from ^2.6 to ^2.8
Update laminas/laminas-diactoros requirement from ^2.6 to ^2.8

Updates the requirements on [laminas/laminas-diactoros](https://github.com/laminas/laminas-diactoros) to permit the latest version.
- [Release notes](https://github.com/laminas/laminas-diactoros/releases)
- [Commits](https://github.com/laminas/laminas-diactoros/compare/2.6.0...2.8.0)

---
updated-dependencies:
- dependency-name: laminas/laminas-diactoros
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@github.com>
slimphp/Slim