Upgrade Windows build to zlib 1.2.3 (a security fix)
diff --git a/Misc/NEWS b/Misc/NEWS
index a6679ad..e457fa1 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -374,6 +374,9 @@
 Build
 -----
 
+- Upgrade Windows build to zlib 1.2.3 which eliminates a potential security
+  vulnerability in zlib 1.2.1 and 1.2.2.
+
 - EXTRA_CFLAGS has been introduced as an environment variable to hold compiler
   flags that change binary compatibility.  Changes were also made to
   distutils.sysconfig to also use the environment variable when used during