replace pkg_resources for python 3.12

[branchvincent]

Python 3.12 has removed bundled setuptools (aka pkg_resources), but it's still used here:

parliament/parliament/__init__.py

Lines 17 to 21 in 20784b7

	iam_definition_path = pkg_resources.resource_filename(__name__, "iam_definition.json")
	iam_definition = json.load(open(iam_definition_path, "r"))
	# And the config data
	config_path = pkg_resources.resource_filename(__name__, "config.yaml")

This means 3.12 users need to manually install setuptools to have a working install:

$ python3.12 -m venv .venv
$ .venv/bin/pip install parliament
$ .venv/bin/parliament --help
Traceback (most recent call last):
  File "/tmp/.venv/bin/parliament", line 5, in <module>
    from parliament.cli import main
  File "/tmp/.venv/lib/python3.12/site-packages/parliament/__init__.py", line 13, in <module>
    import pkg_resources
ModuleNotFoundError: No module named 'pkg_resources'

The recommended replacement is importlib.resources (introduced in python 3.7 and published to PyPI as importlib_resources for backporting). There's a detailed migration guide: https://importlib-resources.readthedocs.io/en/latest/migration.html#pkg-resources-resource-filename

[iainelder]

@branchvincent , thanks for the warning.

Before we fix this, we need to solve some prerequisites:

• Decide which Python versions Parliament should support now
• Run tests across all supported Python versions

Decide which Python versions Parliament should support now

I propose Parliament now should support versions Python 3.8 through 3.12.

Python.org's Devlopers Guide says the oldest supported version is Python 3.8. It will be supported until 2024-10.

setup.py was last updated in 2020-08-13. Back then Python 3.6 was still supported, and Python 3.8 was the latest version.

So the app still claims support for Python 3.6:

parliament/setup.py

Line 47 in 20784b7

python_requires=">=3.6",

And claims compatibility only up to Python 3.8:

parliament/setup.py

Lines 51 to 53 in 20784b7

	"Programming Language :: Python :: 3.6",
	"Programming Language :: Python :: 3.7",
	"Programming Language :: Python :: 3.8",

Run tests across all supported Python versions

Parliament has a script to run unit tests, and according to the README it's up to the developer to run the script and choose the Python environment. It would be great to run the the tests automatically across all supported Python versions.

@branchvincent , we already worked together to solve a similar problem for Sceptre, dropping support for Python 3.7 and adding support for Python 3.12. That lead to a lot of improvements in Sceptre's test infrastructure that I think we can reuse here.

I propose we adapt the unit-tests and get-tox-envlist from Sceptre's check workflow.