Added standard InChi key & string for Argon
Added standard InChi key & string for Argon

Values obtained using IUPAC winchi-1 software from Molfile: https://www.ebi.ac.uk/chebi/searchId.do?chebiId=CHEBI:49475
CoolProp/CoolProp,henningjp/CoolProp,CoolProp/CoolProp,henningjp/CoolProp,henningjp/CoolProp,henningjp/CoolProp,henningjp/CoolProp,CoolProp/CoolProp,henningjp/CoolProp,CoolProp/CoolProp,CoolProp/CoolProp,CoolProp/CoolProp,CoolProp/CoolProp,henningjp/CoolProp,CoolProp/CoolProp,henningjp/CoolProp