ERP5SyncML: remove misuse of Transfer-Encoding: chunked

We do not chunk at this level.

Neither our code nor requests encodes the body this way
and waitress (WSGI) considers the request is corrupted.

It worked so far because Medusa ignores this header field.

product/ERP5SyncML/Transport/HTTP.py

@@ -55,9 +55,7 @@ class HTTPTransport:
       # XXX- Syncml content-type is not supported by Zope server
       # for now disable it until ZServer get patched
       # 'Content-Type' : content_type,
-      # 'Content-Length' : str(len(xml)), XXX-Bad way to compute length
       'Cache-control' : 'no-store',
-      'Transfer-encoding' : 'chunked',
       'Accept' : 'application/vnd.syncml+xml',
       'Accept-Charset' : 'UTF-8',
       'User-Agent' : 'ERP5SyncML Tool',