Fix ModelStateDerived copy ctor

[dweindl]

SUNContext for x_pos_tmp_ wasn't updated after copying.

Hopefully fixes #2607.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 77.60%. Comparing base (2366c2e) to head (bb830ef).
Report is 1 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #2612      +/-   ##
===========================================
- Coverage    77.69%   77.60%   -0.10%     
===========================================
  Files          329      329              
  Lines        21708    21709       +1     
  Branches      1477     1477              
===========================================
- Hits         16866    16847      -19     
- Misses        4831     4851      +20     
  Partials        11       11              

Flag	Coverage Δ
cpp	73.48% <100.00%> (-0.10%)	⬇️
cpp_python	34.14% <0.00%> (-0.01%)	⬇️
petab	36.96% <100.00%> (+0.01%)	⬆️
python	72.20% <100.00%> (-0.09%)	⬇️

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Files with missing lines	Coverage Δ
include/amici/model_state.h	97.02% <100.00%> (+0.02%)	⬆️

... and 3 files with indirect coverage changes