Fix Deprecation Warning when using setuptools >= v61.0.0

[ytmimi]

• Fixes setuptools.config.read_configuration is deprecated #315

[ytmimi]

@matteius thanks for reviewing the PR so quickly ❤️

[matteius]

Thanks for your contribution @ytmimi -- not sure when to do a release next, but I'd like to see if anything in the new pipenv version that gets reported in the next couple weeks traces back to requirementslib or not in case there are more changes to make.

[ytmimi]

@matteius as I understand it requirementslib is vendored in pipenv. Would it be worth opening up a similar issue in the pipenv repo? Just want to know if there's anything else I can do to help here.

[matteius]

@ytmimi sure if you want to track it in pipenv open a ticket that is about -- release new version of requirementslib and vendor it in. Thanks!