postdoc position is closed

[katyhuff]

Summary of changes

Moves the most recent postdoc opening to "closed" status so that it will no longer appear on the live site.

Types of changes

• [x] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)
• [x] I have read the CONTRIBUTING document.
• [x] My code follows the code style of this project.
• [ ] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.
• [ ] I have added tests to cover my changes.
• [x] All new and existing tests passed.

Checklist for Reviewers

Reviewers should use this link to get to the Review Checklist before they begin their review.