Replace `np.math.factorial` -> `math.factorial` #81

	name: ci

	on: [push, pull_request]

	jobs:
	test:
	name: "Python ${{ matrix.python-version }} on ${{ matrix.os }}"
	runs-on: "${{ matrix.os }}"

	strategy:
	matrix:
	python-version: ["3.8", "3.9", "3.10", "3.11", "3.12"]
	os: [ubuntu-latest]

	steps:
	- uses: actions/checkout@v3
	- uses: actions/setup-python@v4
	with:
	python-version: ${{ matrix.python-version }}
	- name: Install dependencies
	run: \|
	set -xe
	python -m pip install --upgrade pip
	pip install flake8 pytest pytest-xdist yapf
	pip install -r requirements.txt
	pip install -r requirements-test.txt
	- name: Lint with flake8
	run: \|
	set -xe
	flake8 . --config=setup.cfg --count --statistics
	- name: Check formatting with yapf
	run: \|
	set -xe
	yapf . --style=setup.cfg --recursive --diff
	- name: Test with pytest
	run: \|
	set -xe
	pytest -n "$(grep -c ^processor /proc/cpuinfo)" hj_reachability

Provide feedback