fix `client.dynamic._Dispatch.QueryInterface`

[Jun Komoda]

THIS IS FOR drop_py2 PLAN! Please see #392.

The client.dynamic._Dispatch.QueryInterface is currently only allowed to be passed a variable argument.

comtypes/comtypes/client/dynamic.py

Lines 85 to 87 in 0fecfea

 def QueryInterface(self, *args): 
     "QueryInterface is forwarded to the real com object." 
     return self._comobj.QueryInterface(*args) 

However, this is a wrapper method for IUnknown.QueryInterface, so I want to change it to a similar argument.

comtypes/comtypes/__init__.py

Line 901 in 0fecfea

 def QueryInterface(self, interface, iid=None): 

It does not change the name of the named arguments that were existing, so I don't think it will break backward compatibility.

[Jun Komoda]

I will work on this.