Check PyCapsule_New return value

[radarhere]

PyCapsule_New may return NULL,

Pillow/src/_imaging.c

Lines 3770 to 3773 in 87e7883

	PyObject *capsule = PyCapsule_New(self->image, IMAGING_MAGIC, _ptr_destructor);
	if (!capsule) {
	return NULL;
	}

but this has not always been applied.