[mlir][python] Bump min pybind11 version to 2.9.0

[rkayaith]

Summary

2.9.0 was released on December 28, 2021, and some following changes
require at least this version.

[stellaraccident]

LGTM - but obviously wait until the bots are updated/pass.

[rkayaith]

So the (only?) bot testing this had its config updated in https://reviews.llvm.org/D150245, but it got shut down before the changes were applied. I'm going to go ahead and land this assuming it'll be updated if/when it comes back.

mlir/cmake/modules/MLIRDetectPythonEnv.cmake

macro(mlir_configure_python_dev_packages)
 
   find_package(Python3 ${LLVM_MINIMUM_PYTHON_VERSION}
     COMPONENTS Interpreter ${_python_development_component} NumPy REQUIRED)
   unset(_python_development_component)
   message(STATUS "Found python include dirs: ${Python3_INCLUDE_DIRS}")
   message(STATUS "Found python libraries: ${Python3_LIBRARIES}")
   message(STATUS "Found numpy v${Python3_NumPy_VERSION}: ${Python3_NumPy_INCLUDE_DIRS}")
   mlir_detect_pybind11_install()
-  find_package(pybind11 2.8 CONFIG REQUIRED)
+  find_package(pybind11 2.9 CONFIG REQUIRED)
   message(STATUS "Found pybind11 v${pybind11_VERSION}: ${pybind11_INCLUDE_DIR}")
   message(STATUS "Python prefix = '${PYTHON_MODULE_PREFIX}', "
                  "suffix = '${PYTHON_MODULE_SUFFIX}', "
                  "extension = '${PYTHON_MODULE_EXTENSION}")
 endmacro()
 
 # Detects a pybind11 package installed in the current python environment
 # and sets variables to allow it to be found. This allows pybind11 to be

mlir/python/requirements.txt

 numpy>=1.19.5, <=1.23.5
-pybind11>=2.8.0, <=2.10.3
+pybind11>=2.9.0, <=2.10.3
 PyYAML>= 5.3.1, <=6.0
 dataclasses>=0.6, <=0.8