test_package issue: subprocess.run needs shell=True

[dmdunla]

On some systems (e.g. Mac), calls to subprocess.run() must include shell=True:

==================================================================================================== short test summary info ====================================================================================================
FAILED tests/test_package.py::test_formatting - FileNotFoundError: [Errno 2] No such file or directory: 'isort <PATH>/pyttb --check --settings-path <PATH>/pyttb'
FAILED tests/test_package.py::test_linting - FileNotFoundError: [Errno 2] No such file or directory: 'pylint <PATH>/pyttb/pyttb/tensor.py <PATH>/pyttb/pyttb/sptensor.py <PATH>/pyttb/pyttb/pyttb_ut...
FAILED tests/test_package.py::test_typing - FileNotFoundError: [Errno 2] No such file or directory: 'mypy -p pyttb  --config-file <PATH>/pyttb/pyproject.toml'
=========================================================================================== 3 failed, 336 passed, 7 warnings in 1.69s ===========================================================================================

Example fix:

subprocess.run(f"isort {root_dir} --check --settings-path {root_dir}", check=True, shell=True)