build(deps): Bump phpoffice/phpspreadsheet

Bumps [phpoffice/phpspreadsheet](https://github.com/PHPOffice/PhpSpreadsheet) from 1.29.8 to 1.29.9.
- [Release notes](https://github.com/PHPOffice/PhpSpreadsheet/releases)
- [Changelog](https://github.com/PHPOffice/PhpSpreadsheet/blob/1.29.9/CHANGELOG.md)
- [Commits](PHPOffice/PhpSpreadsheet@1.29.8...1.29.9)

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

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Author: dependabot[bot]