Add --config parameter to specify pyproject.toml path

[glenrobertson]

Description

For projects that have a pyproject.toml config in a directory other than the root, this allows vulture to accept --config path/to/pyproject.toml (or -c path/to/pyproject.toml).

Related Issue

No issue created or found.

Checklist:

• [x] I have updated the documentation in the README.md file or my changes don't require an update.
• [x] I have added an entry in CHANGELOG.md.
• [x] I have added or adapted tests to cover my changes.
• [x] I have run pre-commit run --all-files to format and lint my code.

[glenrobertson]

@jendrikseipp I'm curious if you agree with this change? I found it useful in my project. If so, I can finish this up and do the checklist items. Thanks!

[jendrikseipp]

Thanks!