Tag beta version for Cantera 3.1.0

[speth]

Changes proposed in this pull request

• Draft release notes for Cantera 3.1.0
• Bump version to 3.1.0b1 (this should be the tagged commit)

This should be merged after #1808.

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 73.26%. Comparing base (e36c9b9) to head (35849bc).
Report is 9 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1810   +/-   ##
=======================================
  Coverage   73.26%   73.26%           
=======================================
  Files         383      383           
  Lines       54620    54620           
  Branches     9099     9099           
=======================================
  Hits        40016    40016           
  Misses      11601    11601           
  Partials     3003     3003           

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[ischoegl]

I assume that #1704 and a fix for #1806 would be added during the beta phase?

[speth]

Hopefully and yes, respectively. I don't think there's a need to hold the beta for either of these.