Update recognized thermal scattering materials for ENDF/B-VIII.1

[paulromano]

Description

I'm currently working on processing the ENDF/B-VIII.1 library for OpenMC and this PR is needed to update our internal list of recognized S(α,β) materials.

Checklist

• I have performed a self-review of my own code
• I have run clang-format (version 15) on any C++ source files (if applicable)
• I have followed the style guidelines for Python 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)

[shimwell]

Thanks for this PR, and the recent nuc data updates. Much appreciated.

Lgtm