Fix Cp2kOutput.spin_polarized() likely not doing what author intended

[janosh]

if ("UKS" or "UNRESTRICTED_KOHN_SHAM" or "LSD" or "SPIN_POLARIZED") in self.data["dft"].values():
            return True

"UKS" or "UNRESTRICTED_KOHN_SHAM" or "LSD" or "SPIN_POLARIZED" short-circuits to "UKS" and so won't return True even if "UNRESTRICTED_KOHN_SHAM" or "LSD" or "SPIN_POLARIZED" are present.