[BUG]: Unknown CMake command "python_add_library" in pybind11NewTools.cmake

Required prerequisites

• Make sure you've read the documentation. Your issue may be addressed there.
• Search the issue tracker and Discussions to verify that this hasn't already been reported. +1 or comment there if it has.
• Consider asking first in the Gitter chat room or in a Discussion.

What version (or hash if on master) of pybind11 are you using?

2.9.1, master

Problem description

Using the new FindPython mode but the old pybind11_add_module, I get the following error:

Errors     << py_binding_tools:cmake /homes/rhaschke/src/ros/logs/py_binding_tools/build.cmake.000.log                                                                                                                                                                         
CMake Error at /usr/lib/cmake/pybind11/pybind11NewTools.cmake:205 (python_add_library):
  Unknown CMake command "python_add_library".
Call Stack (most recent call first):
  /opt/ros/one/share/pybind11_catkin/cmake/pybind11_catkin.cmake:27 (pybind11_add_module)
  CMakeLists.txt:44 (pybind_add_module)

The cmake function python_add_library was renamed to Python_add_library and I think, the corresponding calls in pybind11NewTools.cmake should be adapted accordingly:
https://github.com/pybind/pybind11/blob/741d86f2e3527b667ba85d273a5eea19a0978ef5/tools/pybind11NewTools.cmake#L262
However, I'm surprised that I am the first running into that issue. Maybe I'm missing something else?

Reproducible example code

find_package(Python 3 REQUIRED)
find_package(pybind11 REQUIRED)
pybind11_add_module(py_binding_tools_module src/py_binding_tools.cpp)

Is this a regression? Put the last known working version here if it is.

Not a regression

Inspect tools/pybind11NewTools.cmake around the python_add_library call, then compare it with the FindPython command documented in the issue. Reproduce the failure with the provided find_package and pybind11_add_module example; done means the example configures successfully without the unknown-command error.