mol_to_ccd_cif does not set _chem_comp_atom.pdbx_leaving_atom_flag

[YoavShamir5]

Hi, with the latest version from git cloned and the latest container, generating a user-defined CCD via mol_to_ccd_cif leads to an error during inference:

ValueError: User-defined CCD is missing these keys: {'_chem_comp_atom.pdbx_leaving_atom_flag'}

I did not encounter this before updating to the latest versions, I believe that it arises from enforcing the mandatory fields, but I think that this field is not set by mol_to_ccd_cif. Maybe setting all atom leaving flags of the compound to "N" by default in this function would do the trick?