Bump src/deps/pybind11 from 8a099e4 to 68cbae6

Bumps [src/deps/pybind11](https://github.com/pybind/pybind11) from `8a099e4` to `68cbae6`.
- [Release notes](https://github.com/pybind/pybind11/releases)
- [Commits](pybind/pybind11@8a099e4...68cbae6)

---
updated-dependencies:
- dependency-name: src/deps/pybind11
  dependency-version: 68cbae6641faceeecf39335135206fb92e4b4e3a
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]