The correct configuration for specifying test path in pyproject.toml is testpaths.

[tool.pytest.ini_options]
testpaths = ["src", "tests", "tests/Google-Calendar", "tests/Reclaim", "tests/Todoist"]

Also, in case, for any python files under those,

python_files = ["*.py"]

testpaths: https://docs.pytest.org/en/stable/reference/reference.html#confval-testpaths