Simple TLS configuration doesn't create the ssl_version attribute, use default when mounting adapter

Author: shin-

docker/client.py

@@ -65,7 +65,7 @@ def __init__(self, base_url=None, version=DEFAULT_DOCKER_API_VERSION,
         if isinstance(tls, TLSConfig):
             tls.configure_client(self)
         elif tls:
-            self.mount('https://', ssladapter.SSLAdapter(self.ssl_version))
+            self.mount('https://', ssladapter.SSLAdapter())
         else:
             self.mount('http+unix://', unixconn.UnixAdapter(base_url, timeout))