Include *.properties files in .gitignore

[l-emele]

Summary of the discussion

Include *.properties files in .gitignore. As this affects only the internal handling of git, I don't think that it is necessary to document this in the changelog.

Automation

Closes #1704

PR-Assignee

• [ ] 🐙 Follow the Pull Request Workflow
• [ ] 📝 Update the CHANGELOG.md
• [ ] 📙 Add #'s to term tracker item

Reviewer

• [ ] 🐙 Follow the Reviewer Guide
• [ ] 🐙 Provided feedback and show sufficient appreciation for the work done