Infixowl cleanup

[ghost]

Summary of changes

Whitespace gardening for rdflb/extras/infixowl.py

Checklist

• Checked that there aren't other open pull requests for the same change.
• Added tests for any changes that have a runtime impact.
• Checked that all tests and type checking passes.
• For changes that have a potential impact on users of this project:
  • Updated relevant documentation to avoid inaccuracies.
  • Considered adding additional documentation.
  • Considered adding an example in ./examples for new features.
  • Considered updating our changelog (CHANGELOG.md).
• Considered granting push permissions to the PR branch,
  so maintainers can fix minor issues and keep your PR up to date.

[coveralls]

Coverage remained the same at 90.224% when pulling bba0fcb on gjhiggins:infixowl-coverage into 05dced2 on RDFLib:master.

[aucampia]

Change looks good, and nice bump on coverage.