Fix `surface.center_slab` handling of Slab regions separated by vacuum #4547

DanielYang59 wants to merge 2 commits intomaterialsproject:mastermaterialsproject/pymatgen:masterfrom

DanielYang59:fix-center-slab-handling-of-sep-slab-pbcDanielYang59/pymatgen:fix-center-slab-handling-of-sep-slab-pbcCopy head branch name to clipboard