While working on https://github.com/pybind/pybind11/pull/4674 I came to realize that this include is not needed here.

Note however that the pybind11/cast.h changes under https://github.com/pybind/pybind11/pull/4601 are still needed, therefore pybind11_abseil still requires current pybind11 master.

PiperOrigin-RevId: 533182724