Union type for xml.sax.parse

[starcruiseromega]

The definition of xml.sax.parse is:

def parse(source: str, handler: xml.sax.handler.ContentHandler,
          errorHandler: xml.sax.handler.ErrorHandler = ...) -> None: ...

From the documentation at https://docs.python.org/2.7/library/xml.sax.html#xml.sax.parse and https://docs.python.org/3/library/xml.sax.html#xml.sax.parse, it looks like it the first parameter should be either a string or a file object.

I'll try to put together a PR for this in the next few days.