Update ForwardDiff to 1.

[ofSingularMind]

per ReactiveBayes/RxInfer.jl#509

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 76.05%. Comparing base (be9acdc) to head (bec55a8).
⚠️ Report is 41 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #521      +/-   ##
==========================================
+ Coverage   75.99%   76.05%   +0.06%     
==========================================
  Files         205      205              
  Lines        6077     6119      +42     
==========================================
+ Hits         4618     4654      +36     
- Misses       1459     1465       +6     

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