Bump php-di/php-di from 7.0.7 to 7.0.8

Bumps [php-di/php-di](https://github.com/PHP-DI/PHP-DI) from 7.0.7 to 7.0.8.
- [Release notes](https://github.com/PHP-DI/PHP-DI/releases)
- [Commits](PHP-DI/PHP-DI@7.0.7...7.0.8)

---
updated-dependencies:
- dependency-name: php-di/php-di
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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