Update pybind11-stubgen to v2.4.2

[dagardner-nv]

Description

• Changes required to update pybind11-stubgen
• Between our current version 0.10.5 and 1.0 the tool underwent a complete re-write which removed/changed several command line flags
• Due to the way pybind11-stubgen writes stub files, we now first write the stub then move it to the correct location/name.
• The --ignore-invalid-identifiers flag is needed since at build-time the python extensions are built but not yet installed into the Python env.
• Disable stub building for Cython modules, the reason is that pybind11-stubgen includes the repr output for PyCapsule which includes the memory location of the object, thus causing the stub output to change with each build ref: Optionally disable the # value = ... in Printer sizmailov/pybind11-stubgen#235. In addition to this we don't expose any Cython functions to Python, thus removing the need for building stubs of Cython modules.

Needed for nv-morpheus/Morpheus#2074

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.