Fix typing for inp.py

[mttcnnff]

Description

When doing from bytewax import inp I kept getting the error:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'type' object is not subscriptable

After fiddling with the type hints in the file I was able to get it to work again 🎉

Environment Details:

Python Version

Python 3.8.8

Pip List

Package           Version
----------------- -------
bytewax           0.7.0
distlib           0.3.4
filelock          3.4.2
pbr               5.8.0
pip               22.0.3
platformdirs      2.4.1
setuptools        49.2.1
six               1.16.0
sseclient-py      1.7.2
stevedore         3.5.0
urllib3           1.26.8
virtualenv        20.12.1
virtualenv-clone  0.5.7
virtualenvwrapper 4.8.4

[whoahbot]

Great catch. Thank you so much for the PR! ✨