HHVM ending PHP support

There is a [HHVM blog post](https://hhvm.com/blog/2018/09/12/end-of-php-support-future-of-hack.html) that says HHVM v3.30 will be the last version to support PHP. Maybe TinCanPHP should drop support of HHVM? Or maybe add a note to [README](https://github.com/RusticiSoftware/TinCanPHP/blob/master/README.md)?