Remove .DS_Store that shouldn't be there

[moprak-nrel]

Summary

Remove .DS_Store, looks like it was accidentally added a long time ago.

Pull request type

Please check the type of change introduced:

• [ ] Bugfix
• [ ] Feature
• [ ] Code style update (formatting, renaming)
• [ ] Refactoring (no functional changes, no api changes)
• [ ] Build related changes
• [ ] Documentation content changes
• [x] Other (please describe):