Update cluster_analysis pytest

tests/structural/test_cluster_analysis.py

@@ -79,6 +79,7 @@ def test_get_unique_configurations(self, benchmark, load_molecules):
             cluster_pattern="Cluster_*.xyz",
             r_cut=self.r_cut,
             molecules=load_molecules,
+            mol_num=2,
             type_coord_atoms=["O", "N", "Mg"],
             working_dir=self.working_dir,
             find_top=True,