Bump third_party/pybind11/repo from 8de7772 to 8b03ffa (#28202)

Bumps [third_party/pybind11/repo](https://github.com/pybind/pybind11) from `8de7772` to `8b03ffa`.
- [Release notes](https://github.com/pybind/pybind11/releases)
- [Commits](pybind/pybind11@8de7772...8b03ffa)

---
updated-dependencies:
- dependency-name: third_party/pybind11/repo
  dependency-type: direct:production
...

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