fix: interfaces import

[dtdang]

What I did

Fixes local importing of interfaces directory not being recognized as a local directory.

fixes: #125

How I did it

How to verify it

Checklist

• Passes all linting checks (pre-commit and CI jobs)
• New test cases have been added and are passing
• Documentation has been updated
• PR title follows Conventional Commit standard (will be automatically included in the changelog)

[dtdang]

The issue was that because snekmate used local imports with import interfaces.IERC20Permit as IERC20Permit, we did not consider interfaces as a local dependency but was looking for a package under the name interfaces. This is a bit of a hack solution unless we can convince snekmate to import using import .interfaces.IERC20Permit as IERC20Permit or if there is a better solution but this one solves the issue for now.

[tloriato]

It works! Thank you, @dtdang !

[dtdang]

A better fix for this was done with #128.