Add SVR to sklearn models

[ellaampy]

Currently, sklearn regressions models implemented are random forest, lasso, and ridge.
SVR is also quite standard.

[abdelghanibelgaid]

I’ve added an SVR baseline following the existing scikit-learn pattern:

• SVRModel in cybench/models/svr_model.py using BaseSklearnModel
• Residual variant SVRRes in cybench/models/residual_models.py
• Both models are registered in cybench/runs/run_benchmark.py
• Short names (SVR, SVR-Res) are included in cybench/runs/results_plots.py

PR: #392

Feedback is very welcome.