Added four private SGI tags

Author: radarhere

src/PIL/TiffTags.py

@@ -203,6 +203,11 @@ def lookup(tag: int, group: int | None = None) -> TagInfo:
  531: ("YCbCrPositioning", SHORT, 1),
  532: ("ReferenceBlackWhite", RATIONAL, 6),
  700: ("XMP", BYTE, 0),
+ # Four private SGI tags
+ 32995: ("Matteing", SHORT, 1),
+ 32996: ("DataType", SHORT, 0),
+ 32997: ("ImageDepth", LONG, 1),
+ 32998: ("TileDepth", LONG, 1),
  33432: ("Copyright", ASCII, 1),
  33723: ("IptcNaaInfo", UNDEFINED, 1),
  34377: ("PhotoshopInfo", BYTE, 0),