[BUG FIX] Fix missing '@ti.kernel' decorator to 'PBDSolver._kernel_get_particles_vel'. (#1807)

Author: duburcqa

genesis/engine/solvers/pbd_solver.py

@@ -923,6 +923,7 @@ def set_animate_particles_by_link(
         envs_idx = self._scene._sanitize_envs_idx(envs_idx)
         self._sim._coupler.kernel_attach_pbd_to_rigid_link(particles_idx, envs_idx, link_idx, links_state)
 
+    @ti.kernel
     def _kernel_get_particles_vel(
         self,
         particle_start: ti.i32,