Bump symfony/process from 3.4.24 to 3.4.26

Bumps [symfony/process](https://github.com/symfony/process) from 3.4.24 to 3.4.26.
- [Release notes](https://github.com/symfony/process/releases)
- [Changelog](https://github.com/symfony/process/blob/master/CHANGELOG.md)
- [Commits](https://github.com/symfony/process/compare/v3.4.24...v3.4.26

)

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