Require 0.2.3 CPM

This includes vendor parsing so that we can reproduced the index.json

Author: theotherjimmy

requirements.txt

@@ -23,4 +23,4 @@ git+https://github.com/armmbed/[email protected]
 icetea>=1.2.1,<1.3
 pycryptodome>=3.7.2,<=3.7.3
 pyusb>=1.0.0,<2.0.0
-cmsis-pack-manager>=0.2.2,<0.3.0
+cmsis-pack-manager>=0.2.3,<0.3.0