Removed Content-Length header

This header should be populated automatically, whereas providing it
may cause nginx to fail the request with HTTP 400 if the actual content
length does not match.

Author: glpatcern

cs3client/file.py

@@ -226,7 +226,6 @@ def write_file(
             else:
                 headers = {
                     "Upload-Length": str(size),
-                    "Content-Length": str(size),
                     "X-Reva-Transfer": protocol.token,
                     **dict([auth_token]),
                     "X-Lock-Id": lock_id,