Update core.py

[ssurbhi560]

Description

Since visit_Str() is deprecated in Python3.8 so adding the visit_Constant() method . #175

Checklist:

• [x] My code follows the code style of this project.
• [ ] My change requires a change to the documentation in the README file.
• [ ] I have updated the documentation accordingly.
• [ ] I have added an entry in NEWS.rst.
• [ ] I have added tests to cover my changes.
• [ ] All new and existing tests passed.

[RJ722]

Thank you @ssurbhi560 for the PR!

Your tests are failing because currently Vulture is reporting visit_Constant method as unused (because it's dynamically called).

You can add the following in vulture/whitelists/ast_whitelist.py and the tests would go green again:

whitelist_node_visitor.visit_Constant

However, I'm not entirely sure how we can add a test case for this new functionality.

[jendrikseipp]

I took the liberty of fixing this here: https://github.com/jendrikseipp/vulture/commit/c5b6417a03736fc25736ea1dcd23385c7c462089