[python] setup.py template should be updated to include Python 3.13 in classifiers

[kristapratico]

We support 3.13, we should include it in the classifiers:

typespec/packages/http-client-python/generator/pygen/codegen/templates/packaging_templates/setup.py.jinja2

Lines 54 to 65 in 29fbfec

	classifiers=[
	"Development Status :: {{ dev_status }}",
	"Programming Language :: Python",
	"Programming Language :: Python :: 3 :: Only",
	"Programming Language :: Python :: 3",
	"Programming Language :: Python :: 3.8",
	"Programming Language :: Python :: 3.9",
	"Programming Language :: Python :: 3.10",
	"Programming Language :: Python :: 3.11",
	"Programming Language :: Python :: 3.12",
	"License :: OSI Approved :: MIT License",
	],

I know we're moving to pyproject.toml soon, but not sure if we have a template for that yet.

[msyyc]

We shall also add py3.13 check in CI to make sure we fully support it.

[msyyc]

Pending on azure-core update python 3.13 Azure/azure-sdk-for-python#39595