Fix onConnect docstring regarding return value
Fix onConnect docstring regarding return value

The docstring mentioned a ConnectionAccept to be returned, whilst this model exists it doesn't seem to be used and the actual expected return value is str.
crossbario/autobahn-python,crossbario/autobahn-python,oberstet/autobahn-python,oberstet/autobahn-python,oberstet/autobahn-python,crossbario/autobahn-python,tavendo/AutobahnPython