Update Pybind11 to v2.12.0 for numpy v2 support

[yuzawa-san]

• I upgraded to numpy 2.0.0 recently and found the numpy image logic was broken
• I found that numpy had some breaking changes which caused the itemsize() call to return 0. see [BUG]: latest pybind11 (2.11.1) version not supporting numpy 2.0 pybind/pybind11#5009
• this was fixed API: Make numpy.h compatible with both NumPy 1.x and 2.x pybind/pybind11#5050 and released in https://github.com/pybind/pybind11/releases/tag/v2.12.0
• i used the same methodology as Update Pybind11 to v2.10.0 #2660 (copying the files)
• i tested locally with the numpy 1.26.4 and 2.0.0
• open question: should i make this a git submodule?

[davisking]

Nice, thanks for doing this :)