Update AWS s3 to aliyun OSS for downloading Python

bin/steps/python

@@ -41,7 +41,7 @@ if [ ! "$SKIP_INSTALL" ]; then
 
     mcount "version.python.$PYTHON_VERSION"
 
-    if ! curl "https://lang-python.s3.amazonaws.com/$STACK/runtimes/$PYTHON_VERSION.tar.gz" -s | tar zxv -C .heroku/python &> /dev/null; then
+    if ! curl "http://helmsman-firmware.oss-cn-hongkong.aliyuncs.com/dokku/$STACK/$PYTHON_VERSION.tar.gz" -s | tar zxv -C .heroku/python &> /dev/null; then
       puts-warn "Requested runtime ($PYTHON_VERSION) is not available for this stack ($STACK)."
       puts-warn "Aborting.  More info: https://devcenter.heroku.com/articles/python-support"
       exit 1