CMake: Correct zlib version number.

CMakeLists.txt

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 8a8fde7..1b31303 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -3,7 +3,7 @@
 project(
     zlib
     LANGUAGES C
-    VERSION 1.4.1.1
+    VERSION 1.3.1.2
     HOMEPAGE_URL "https://zlib.net/"
     DESCRIPTION "a general-purpose lossless data-compression library")