Custom floats do not respect np.set_printoptions

[jakevdp]

Reported in jax-ml/jax#18820

The repr code is here:

ml_dtypes/ml_dtypes/_src/custom_float.h

Lines 356 to 362 in d0519a5

	PyObject* PyCustomFloat_Repr(PyObject* self) {
	T x = reinterpret_cast<PyCustomFloat<T>*>(self)->value;
	float f = static_cast<float>(x);
	std::ostringstream s;
	s << (std::isnan(f) ? std::abs(f) : f);
	return PyUnicode_FromString(s.str().c_str());
	}

@hawkinsp points out that we could probably make this work by printing via np.float32 rather than via python float