0.15.0 is released

This release is backward compatible but please see the [CHANGELOG](https://github.com/igordejanovic/parglare/blob/master/CHANGELOG.md#0150-released-2021-07-14) and [Release Notes](http://www.igordejanovic.net/parglare/latest/release_notes/release_0_15/) before upgrade.
Signed packages can be found on [the release page](https://github.com/igordejanovic/parglare/releases).