Fix SUNDIALS 7.x compatibility/library list checks

[speth]

Changes proposed in this pull request

• Correct SUNDIALS version checks so sundials_core is linked for SUNDIALS 7.0 and newer, and the warning about being untested only occurs for versions newer than 7.2.0.

Checklist

• The pull request includes a clear description of this code change
• Commit messages have short titles and reference relevant issues
• Build passes (scons build & scons test) and unit tests address code coverage
• Style & formatting of contributed code follows contributing guidelines
• The pull request is ready for review

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 73.54%. Comparing base (1ef52c9) to head (0b53509).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1828      +/-   ##
==========================================
- Coverage   73.54%   73.54%   -0.01%     
==========================================
  Files         383      383              
  Lines       54653    54653              
  Branches     9105     9105              
==========================================
- Hits        40197    40194       -3     
- Misses      11458    11460       +2     
- Partials     2998     2999       +1     

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