Fix Examples CI

[tmigot]

https://github.com/JuliaSmoothOptimizers/SolverBenchmark.jl/actions/runs/11805344788/job/32887581626?pr=167

The issue is that AmplNLReader does not support NLPModel linear API, see JuliaSmoothOptimizers/AmplNLReader.jl#127 . So, using Percival on inequality constrained problem failed because it uses SlackModel that rely on the linear API.

Potential solutions:

1. Add linear API to AmplNLReader
2. Update the Examples script
3. Change the way SlackModel works to be flexible to unimplemented linear API.

[dpo]

Solution 1 would be great, but not obvious to implement. I have prototype code but it doesn't quite work.

Solution 3 would be "easy" to implement and may be the most flexible.