add check for deprecated rawmodes when creating an ImagePalette

Tests/test_imagepalette.py

@@ -158,6 +158,12 @@ def test_rawmode_valueerrors(tmp_path: Path) -> None:
         palette.save(f)
 
 
+@pytest.mark.parametrize("rawmode", Image._DEPRECATED_RAWMODES)
+def test_rawmode_deprecated(rawmode: str) -> None:
+    with pytest.warns(DeprecationWarning):
+        ImagePalette.raw(rawmode, b"")
+
+
 def test_getdata() -> None:
     # Arrange
     data_in = list(range(256)) * 3

src/PIL/ImagePalette.py

@@ -209,6 +209,16 @@ class ImagePalette:
 
 
 def raw(rawmode: str, data: Sequence[int] | bytes | bytearray) -> ImagePalette:
+    from . import Image
+    from ._deprecate import deprecate
+
+    if rawmode in Image._DEPRECATED_RAWMODES:
+        deprecate(
+            f"rawmode {rawmode}",
+            12,
+            replacement=f"rawmode {Image._DEPRECATED_RAWMODES[rawmode]}",
+        )
+
     palette = ImagePalette()
     palette.rawmode = rawmode
     palette.palette = data