fix compatibility with the latest pymatgen (#1126)

Fix #1108.

Note: tests do not cover this case.

Author: njzjz

dpgen/data/gen.py

@@ -362,7 +362,7 @@ def make_super_cell_poscar(jdata):
     # minor bug for element symbol behind the coordinates
     from_struct = Structure.from_file(from_file)
     from_struct.make_supercell(super_cell)
-    from_struct.to("poscar", to_file)
+    from_struct.to(to_file, "poscar")
 
     # make system dir (copy)
     lines = open(to_file, "r").read().split("\n")