Added four private SGI TIFF tags (#9245)

Author: hugovk

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),