Bump submodule for latest release of pybind11

[cbm755]

I think this fixes building on Python 3.11. Fixes #18.

---

I'm not used to working with git submodules, so I hope I've done this right. The idea was to bump the including (submodule) for pybind11 to the latest release.

After this change, pip install . works for me on Python 3.11. I have not extensively tested.

[cbm755]

In case its helpful for anyone else, I just figured out how to Pip-install directly from that branch:

pip install git+https://github.com/cbm755/py-lapsolver@pybind11_bump

(after usually python3 -m pip install -U pip if your OS is a little old)

[cheind]

@cbm755 thanks! I hope I find the time soon to test this PR and merge. Never mind the appveyor failures, I think they are not relevant. Will add a github-actions based approach instead.

[CarlosRDomin]

Any update? This branch indeed fixes our issues on python 3.11 :)

[cheind]

thanks for the PR, I've just merged a new update to pybind #20