Bump phpoffice/phpspreadsheet from 2.3.5 to 2.3.6

Bumps [phpoffice/phpspreadsheet](https://github.com/PHPOffice/PhpSpreadsheet) from 2.3.5 to 2.3.6.
- [Release notes](https://github.com/PHPOffice/PhpSpreadsheet/releases)
- [Changelog](https://github.com/PHPOffice/PhpSpreadsheet/blob/2.3.6/CHANGELOG.md)
- [Commits](PHPOffice/PhpSpreadsheet@2.3.5...2.3.6)

---
updated-dependencies:
- dependency-name: phpoffice/phpspreadsheet
  dependency-type: indirect
...

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