Tool for automatically converting a pybind11 based project to nanobind

[blozano-tt]

Would it be feasible for the open source community to develop a tool that can automatically convert a code base that uses pybind11 to nanobind?

Motivation:

We have spent many months (> 6 months) trying to migrate a large code base from pybind11 to nanobind. Even after getting it to compile, we are seeing runtime issues. My colleague is attempting to write a custom clang-tidy check with FIXITs to do some conversion, because the python interface continues to change on main, and rebasing manually is a nightmare.

[oremanj]

Keep an eye on
#1140
pybind/pybind11#5800
which will hopefully make this process easier to do incrementally!