acados/acados: v0.2.4

• Zoro followup by @FreyJo in https://github.com/acados/acados/pull/960
• GNRK: Gauss-Newton Runge-Kutta: IRK with nonlinear-least squares by @FreyJo in https://github.com/acados/acados/pull/698
• Python get_stats returns float or int instead of single element numpy array and fix cython for custom path by @aghezz1 in https://github.com/acados/acados/pull/961
• python interface: get the gradient of the optimal value function by @sandmaennchen in https://github.com/acados/acados/pull/963
• Cleanup by @FreyJo in https://github.com/acados/acados/pull/965
• refactored optionally verbose system calls in python interface by @tudoroancea in https://github.com/acados/acados/pull/962

BREAKING: change return types of get_stats in Python

Full Changelog: https://github.com/acados/acados/compare/v0.2.3...v0.2.4