Fixed a memory leak that was introduced with incorrect usage of the Python weak
reference API in pysqlite 2.2.1.

Bumbed pysqlite version number to upcoming pysqlite 2.3.1 release.
diff --git a/Modules/_sqlite/module.h b/Modules/_sqlite/module.h
index 00eff1f..3fdac61 100644
--- a/Modules/_sqlite/module.h
+++ b/Modules/_sqlite/module.h
@@ -25,7 +25,7 @@
 #define PYSQLITE_MODULE_H
 #include "Python.h"
 
-#define PYSQLITE_VERSION "2.3.0"
+#define PYSQLITE_VERSION "2.3.1"
 
 extern PyObject* Error;
 extern PyObject* Warning;