Tests should be passed on python3.9

[kujyp]

pytest-mock/setup.py

Line 12 in 9e1464b

python_requires=">=3.5",

pytest-mock deployed as python3.9 installable.
pytest-mock-3.3.1.tar.gz
pytest_mock-3.3.1-py3-none-any.whl
https://pypi.org/simple/pytest-mock/

So, in my opinion, python3.9 should be added on CI workflow.

pytest-mock/.github/workflows/main.yml

Lines 13 to 23 in 9e1464b

	python: ["3.5", "3.6", "3.7", "3.8"]
	os: [ubuntu-latest, windows-latest]
	include:
	- python: "3.5"
	tox_env: "py35"
	- python: "3.6"
	tox_env: "py36"
	- python: "3.7"
	tox_env: "py37"
	- python: "3.8"
	tox_env: "py38"

[kujyp]

actions/setup-python supports python 3.9 from Oct, 2020
actions/setup-python#148 (comment)