Gets the earliest PDF version that has this colour space (Table 61), for a writer raising the file's version.
public override PdfVersion MinimumVersion { get; }
ISO 32000-2 §8.6.3: the device spaces, CalGray, CalRGB, Lab and Indexed 1.1 (an Indexed lookup string 1.2), Pattern and Separation 1.2, ICCBased and DeviceN 1.3 (DeviceN attributes 1.6).