Replace attrdict with metadict

[abocquet]

What?

pyEPR uses a package called AttrDict. AttrDict is not compatible with python 3.9 and above, so one has to use an old version of python to work with pyEPR. This change aims at fixing this by replacing AttrDict with another package that is compatible with later versions of python.

We replace AttrDict (https://pypi.org/project/attrdict/) with MetaDict (https://pypi.org/project/metadict/0.1.2/). Both packages expose dictionary-like objects so the change will be totally transparent to the user.

How?

In the code, we have

from attrdict import AttrDict as Dict

# everywhere else:
from . import Dict

we just had to replace it with

from metadict import MetaDict as Dict

Does it work?

Yes, it works with the demo script from pyEPR, tested on Windows with python 3.7. Feel free to test it on your own machine before approving