Bump python/pybind11 from a406a62 to 31d7c87 (#135)

Bumps [python/pybind11](https://github.com/pybind/pybind11) from `a406a62` to `31d7c87`.
- [Release notes](https://github.com/pybind/pybind11/releases)
- [Commits](pybind/pybind11@a406a62...31d7c87)

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

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>