Lower case for labels in issue templates

[dalmijn]

Issue addressed

Fixes

Explanation

Explain how you addressed the bug/feature request, what choices you made and why.

Checklist

• [x] Updated tests or added new tests
• [x] Branch is up to date with main
• [x] Tests & pre-commit hooks pass
• [x] Updated documentation if needed

Additional Notes (optional)

Add any additional notes or information that may be helpful.