chore(release): 1.0.0-alpha.59 [skip ci]

# [1.0.0-alpha.59](https://code.podlibre.org/podlibre/castopod-host/compare/v1.0.0-alpha.58...v1.0.0-alpha.59) (2021-06-15)

### Bug Fixes

* check that additional files are valid when creating episode ([eac5bc87](https://code.podlibre.org/podlibre/castopod-host/commit/eac5bc876de125e1fe08d1b89f767a04fc0fbfb6))