Add DeprecatedIn09
diff --git a/src/cryptography/utils.py b/src/cryptography/utils.py
index 0f8cbb2..31d7275 100644
--- a/src/cryptography/utils.py
+++ b/src/cryptography/utils.py
@@ -11,6 +11,7 @@
 
 
 DeprecatedIn08 = DeprecationWarning
+DeprecatedIn09 = DeprecationWarning
 
 
 def read_only_property(name):