Fix policyengine-core so that policyengine-us does not crash with fatal error

[martinholmer]

I am using the 0.770.0 version of policyengine-us and the 2.21.1 version of policyengine-core, which setup.py says is all that is required:

policyengine-us/setup.py

Lines 34 to 50 in 9c5ec52

	install_requires=[
	"click==8.1.3",
	"h5py",
	"microdf_python",
	"pandas",
	"pathlib",
	"policyengine-core>=2.20.0,<3",
	"pytest",
	"pytest-dependency",
	"pyyaml",
	"requests",
	"scipy==1.10.1",
	"synthimpute",
	"tables==3.8.0",
	"tabulate",
	"tqdm",
	],

.

But yet when I run the MA and OH state income tests (see issue #993), they all fail with this error message:

File "//Users/mrh/anaconda3/envs/policyengine-us/lib/python3.10/site-packages/policyengine_core/simulations/simulation.py", line 535, in _calculate
    cache_path = self._get_macro_cache(variable_name, str(period))
File "//Users/mrh/anaconda3/envs/policyengine-us/lib/python3.10/site-packages/policyengine_core/simulations/simulation.py", line 1347, in _get_macro_cache
    self.dataset.file_path.parent
AttributeError: 'str' object has no attribute 'parent'