Fix minor typo in the rest format in the enum docs (GH-24335)

diff --git a/Doc/library/enum.rst b/Doc/library/enum.rst
index b27c552..4d6f2c3 100644
--- a/Doc/library/enum.rst
+++ b/Doc/library/enum.rst
@@ -1364,7 +1364,7 @@
     True
 
 There is a new boundary mechanism that controls how out-of-range / invalid
-bits are handled: ``STRICT``, ``CONFORM``, ``EJECT`', and ``KEEP``:
+bits are handled: ``STRICT``, ``CONFORM``, ``EJECT``, and ``KEEP``:
 
   * STRICT --> raises an exception when presented with invalid values
   * CONFORM --> discards any invalid bits