pony-stable: 0.1.3 -> 0.1.4

Semi-automatic update generated by https://github.com/ryantm/nixpkgs-update tools.

This update was made based on information from https://repology.org/metapackage/pony-stable/versions.

These checks were done:

- built on NixOS
- /nix/store/lb8ipik1qmjzhjnj04iv92as8k763cpd-pony-stable-0.1.4/bin/stable passed the binary check.
- 1 of 1 passed binary check by having a zero exit code.
- 0 of 1 passed binary check by having the new version present in output.
- found 0.1.4 with grep in /nix/store/lb8ipik1qmjzhjnj04iv92as8k763cpd-pony-stable-0.1.4
- directory tree listing: https://gist.github.com/3550bd75a6690902598b047ba7dba1a9
- du listing: https://gist.github.com/3f202ed132af36d390ed59ab7da008a6