style: remove unused imports

[vil02]

Brief Summary of Changes

I found some unused imports - this PR removes them.

What does this PR address?

• [x] GitHub issue (Add reference - #345)
• [x] Refactoring
• [ ] New feature
• [ ] Bug fix
• [ ] Adds more tests

Are tests included?

• [ ] Yes
• [x] No

Reviewer, please note:

I did not create an issue for that, but clearly I can if really necessary.

This was created in a spirit of #337. Fixes #345.

Checklist:

• [x] My code follows the code style of this project.
• [ ] My change requires a change to the documentation.
• [ ] I ran the full test suite before pushing the changes and all the tests pass.