[Bug #1049826] Update version of zlib referenced in text

Doc/lib/libzlib.tex

@@ -9,8 +9,8 @@
 For applications that require data compression, the functions in this
 module allow compression and decompression, using the zlib library.
 The zlib library has its own home page at
-\url{http://www.gzip.org/zlib/}.  Version 1.1.3 is the
-most recent version as of September 2000; use a later version if one
+\url{http://www.gzip.org/zlib/}.  Version 1.2.1 is the
+most recent version as of October 2004; use a later version if one
 is available.  There are known incompatibilities between the Python
 module and earlier versions of the zlib library.