Add explicit versions to packages

Author: graingert

setup.cfg

@@ -12,8 +12,8 @@ description-file =
     CHANGES.rst
 home-page = https://github.com/graingert/python-clamd
 requires-dist =
-    setuptools
-    six
+    setuptools (0.7)
+    six (1.3)
 classifier = License :: OSI Approved :: GNU Library or Lesser General Public License (LGPL)
 
 [files]
@@ -25,8 +25,7 @@ extra_files =
 
 [backwards_compat]
 tests-require =
-    six
-    nose
+    nose (1.3)
 
 [test]
 test-suite = nose.collector