test: Fix wsgi.input type in one testWSGI case.

caucase/test.py

@@ -1872,7 +1872,7 @@ class CaucaseTest(unittest.TestCase):
         'PATH_INFO': '/cors',
         'REQUEST_METHOD': 'POST',
         'CONTENT_TYPE': 'application/x-www-form-urlencoded',
-        'wsgi.input': StringIO(urlencode(input_dict)),
+        'wsgi.input': StringIO(utils.toUnicode(urlencode(input_dict))),
       }
       base_request_reader_dict.update(kw)
       return base_request_reader_dict