Update examples/stlib/PrefabScene_beginner.py

Co-authored-by: EulalieCoevoet <eulalie.coevoet@gmail.com>

Author: bakpaul

examples/stlib/PrefabScene_beginner.py

@@ -1,7 +1,7 @@
-from stlib.prefabs.materials.rigid import Rigid
-from stlib.prefabs.materials.deformable import Deformable
-from stlib.prefabs.geometries.cube import CubeParameters
-from stlib.prefabs.geometries.file import FileParameters
+from stlib.materials.rigid import Rigid
+from stlib.materials.deformable import Deformable
+from stlib.geometries.cube import CubeParameters
+from stlib.geometries.file import FileParameters
 from splib.simulation.headers import setupLagrangianCollision
 from splib.simulation.linear_solvers import addLinearSolver
 from splib.simulation.ode_solvers import addImplicitODE