[appveyor] enable Github Releases deployment on tags
[appveyor] enable Github Releases deployment on tags

encrypted my api key following these instructions:
https://www.appveyor.com/docs/deployment/github/

obp/py-zopfli,obp/zopfli,obp/zopfli,obp/py-zopfli,obp/zopfli,obp/py-zopfli