Update pd-buddy-python dependency

The GUI still works fine with version 0.1, but should be used with 0.2
now that the PID is assigned.

README.md

 * GTK+ 3.22
 * Python 3.6
 * python-gobject 3.22
-* pd-buddy-python 0.1
+* pd-buddy-python 0.2
 
 ## Usage