Update to Optim@2

[devmotion]

Update Survival to Optim@2.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 92.85714% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 99.32%. Comparing base (8740666) to head (28a859b).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
src/cox.jl	92.85%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #69      +/-   ##
==========================================
- Coverage   99.65%   99.32%   -0.33%     
==========================================
  Files           6        6              
  Lines         286      297      +11     
==========================================
+ Hits          285      295      +10     
- Misses          1        2       +1     

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