Update stackless-dev to check for Python 3.5

plugins/python-build/share/python-build/stackless-dev

@@ -1,4 +1,4 @@
 #require_gcc
 install_package "openssl-1.0.2g" "https://www.openssl.org/source/openssl-1.0.2g.tar.gz#b784b1b3907ce39abf4098702dade6365522a253ad1552e267a9a0e89594aa33" mac_openssl --if has_broken_mac_openssl
 install_package "readline-6.3" "http://ftpmirror.gnu.org/readline/readline-6.3.tar.gz#56ba6071b9462f980c5a72ab0023893b65ba6debb4eeb475d7a563dc65cafd43" standard --if has_broken_mac_readline
-install_hg "stackless-dev" "http://hg.python.org/stackless" "default" standard verify_py33 ensurepip
+install_hg "stackless-dev" "http://hg.python.org/stackless" "default" standard verify_py35 ensurepip