Fixed Python dependency check.

setup.py

@@ -30,8 +30,8 @@ from setuptools.extension import Extension
 import os
 import sys
 
-if sys.version_info < (2, 4, 2):
-    print "This version of ZODB requires Python 2.4.2 or higher"
+if sys.version_info < (2, 5):
+    print "This version of ZODB requires Python 2.5 or higher"
     sys.exit(0)
 
 # The (non-obvious!) choices for the Trove Development Status line: