Replace obsolete string.join with ''.join

[thomdask]

sting.join is not a thing since a long time. Replace it with "".join otherwise this exception is raised

File "/some/path/lib/python3.11/site-packages/SOAPpy/Parser.py", line 1095, in _parseSOAP
parser.parse(inpsrc)
File "/usr/lib/python3.11/xml/sax/expatreader.py", line 111, in parse
xmlreader.IncrementalParser.parse(self, source)
File "/usr/lib/python3.11/xml/sax/xmlreader.py", line 125, in parse
self.feed(buffer)
File "/usr/lib/python3.11/xml/sax/expatreader.py", line 217, in feed
self._parser.Parse(data, isFinal)
File "../Modules/pyexpat.c", line 468, in EndElement
File "/usr/lib/python3.11/xml/sax/expatreader.py", line 381, in end_element_ns
self._cont_handler.endElementNS(pair, None)
File "/some/path/lib/python3.11/site-packages/SOAPpy/Parser.py", line 232, in endElementNS
string.join(self._data, "").strip() != '':
AttributeError: module 'string' has no attribute 'join'

[ppena-LiveData]

I don't understand how this repo is called SOAPpy-py3 and it still references sting.join(), which as far as I can tell was already gone in Python 3.0 so has never existing for Python 3.