Remove needless Dependabot ignore directive

[jsf9k]

🗣 Description

This pull request removes a now-unnecessary Dependabot ignore directive.

💭 Motivation and context

The pin against ansible-lint was removed in commit 32993325e11d482e078e05d27c3269e6401a8f53, so there is no longer any need for the Dependabot ignore directive.

🧪 Testing

All automated tests pass.

✅ Pre-approval checklist

• [x] This PR has an informative and human-readable title.
• [x] Changes are limited to a single goal - eschew scope creep!
• [x] All relevant type-of-change labels have been added.
• [x] I have read the CONTRIBUTING document.
• [x] These code changes follow cisagov code standards.
• [x] All new and existing tests pass.