Allow users to specify custom coefficient values for predict

[palday]

• add entry in NEWS.md
• after opening this PR, add a reference and run docs/NEWS-update.jl to update the cross-references.
• I've bumped the version appropriately

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.90%. Comparing base (2228a9a) to head (5eb9069).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #916      +/-   ##
==========================================
+ Coverage   94.89%   94.90%   +0.01%     
==========================================
  Files          38       38              
  Lines        3958     3967       +9     
==========================================
+ Hits         3756     3765       +9     
  Misses        202      202              

Flag	Coverage Δ
current	94.59% <100.00%> (+0.01%)	⬆️
minimum	94.80% <100.00%> (-0.04%)	⬇️
nightly	94.59% <100.00%> (+0.01%)	⬆️

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