Description

I've been working on the benchmarks from the MIT CRPG repository, and I've encountered some geometry.xml files (e.g., example) that are still using the old format. In this format, surface elements contain child tags rather than attributes, which prevents them from being loaded directly using the OpenMC Python API.

To address this, I have updated the openmc-update-inputs to accommodate these changes and ensure compatibility with the newer format.

Fixes # (issue)

Checklist

• I have performed a self-review of my own code
• I have followed the style guidelines for Python source files (if applicable)
• I have run clang-format (version 15) on any C++ source files (if applicable)
• I have made corresponding changes to the documentation (if applicable)
• I have added tests that prove my fix is effective or that my feature works (if applicable)