Add #directory to Dependabot::Dependency

[landongrindheim]

What are you trying to accomplish?

This is a concept which has been deemed to be missing. The effect of this is that when a pull request exists for a group, without there being knowledge of a directory, individual pull requests are then created. By adding #directory to Dependabot::Dependency, we'll be able to prevent this.

We'll need to start setting #directory in future changes. By leaving it in its current state, it will be available to the updater (for said future changes), and to consumers of the library.

Anything you want to highlight for special attention from reviewers?

While this change adds an attr_accessor, #directory is not being written or read anywhere yet.

How will you know you've accomplished your goal?

Checklist

• I have run the complete test suite to ensure all tests and linters pass.
• I have thoroughly tested my code changes to ensure they work as expected, including adding additional tests for new functionality.
• I have written clear and descriptive commit messages.
• I have provided a detailed description of the changes in the pull request, including the problem it addresses, how it fixes the problem, and any relevant details about the implementation.
• I have ensured that the code is well-documented and easy to understand.