NetMessenger Handle isn't Python 3 compatible

[neatsketched]

Since upgrading from python2 to python3, I've found the way the loads method from the pickle module has changed and no longer accepts a string as an argument

According to the documentation, the python2 version accepts one string

pickle.loads(string)

Where as the new python3 version accepts a bytes_object

pickle.loads(bytes_object, *, fix_imports=True, encoding="ASCII", errors="strict")

Line of code I'm referencing:

panda3d/direct/src/distributed/NetMessenger.py

Line 111 in ffe4f38

sentArgs=loads(di.getString())