CI failures in test_model_diagnostics.py::TestDegeneracyHunter::test_solve_candidates_milp

[lbianchi-lbl]

• Affects the most likely unrelated PRs #1342 and #1350
• Current guess is that it's due to a new version of ampl-module-scip being released (see https://portal.ampl.com/dl/pypi/ampl-module-scip/)
• Will try to open a PR to pin the ampl-module-scip version to the last available one known to be working
  • Judging from https://github.com/IDAES/idaes-pse/actions/runs/8021757576/job/21914589132#step:5:1362, this seems to be 20240121