make rigid contact less stiff

examples/tutorials/advanced_hybrid_robot.py

@@ -21,6 +21,7 @@
         gravity=(0, 0, -9.8),
         enable_collision=True,
         enable_self_collision=False,
+        contact_resolve_time=0.02,  # avoid the rigid contact solver being too stiff otherwise will cause large impulse (especially we have small dt for rigid solver)
     ),
     mpm_options=gs.options.MPMOptions(
         dt=dt,