Bump twig/twig from 2.14.11 to 2.15.3 in /generator (#369)

Bumps [twig/twig](https://github.com/twigphp/Twig) from 2.14.11 to 2.15.3.
- [Release notes](https://github.com/twigphp/Twig/releases)
- [Changelog](https://github.com/twigphp/Twig/blob/v2.15.3/CHANGELOG)
- [Commits](twigphp/Twig@v2.14.11...v2.15.3)

---
updated-dependencies:
- dependency-name: twig/twig
  dependency-type: direct:production
...

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