setup: set minimum required versions for contruct and cmd2

* 'String' class renamed to 'PaddedString' in construct v2.9
* 'CommandSet' was introduced with with cmd2 v1.3.0

Change-Id: I170a9e896612086c4b0535cd6d950346897abc3b
diff --git a/setup.py b/setup.py
index 6b4335a..75d7d20 100644
--- a/setup.py
+++ b/setup.py
@@ -12,9 +12,9 @@
         "pyscard",
         "serial",
         "pytlv",
-        "cmd2",
+        "cmd2 >= 1.3.0",
         "jsonpath-ng",
-        "construct",
+        "construct >= 2.9",
     ],
     scripts=[
         'pySim-prog.py',