Pyomo/pyomo 6.9.4 on GitHub

Highlights of the 6.9 release series

Removed support for Python 3.8
New Logic-Based Discrete-Steepest Descent Algorithm in GDPOpt
New External Function for Cubic Spline Interpolation
New ASL External Functions Library
New solver interfaces:
- Support for upcoming knitro Python package
- v2: Ongoing solver interface refactor
...and of course numerous minor bug fixes and performance enhancements

General
- Cleanup collections module (#3708)
- Work around environments where IntEnum.__doc__ is None (#3711)
- Standardize 'multiprocessing' deferred import (#3702)
- Resolve capture_output(capture_fd=True) deadlock on Windows (#3679)
Core
- Bugfix: standard form with fixed variables (#3704)
DAE
- Fix simulator bug (#3692)
Solver Interfaces
- Add reporting of SCIP node count to solver results (#3691)
- Create API version attribute for different solver generations (#3699)
- Ipopt_v2: update options processing (#3693)
- Expanded LegacySolverWrapper fixes (#3700)
Testing
- Update GAMS download to new "latest" link (#3706)
- New TPL cache version on GHA workflows (#3705)
Contributed Packages
- benders: Added support for HiGHS solver (#3686)
- DoE: Add grey box objectives (#3606)
- Parmest: Correct two very old test skips (#3697)
- Parmest: Extend capability for weighted SSE objective (#3535)
- PyROS: Modify two solver tests (#3694)
- sensitivity_toolbox: Sensitivity calculation for named expressions (#3685)