chore(release): 1.0.0-alpha.40 [skip ci]

# [1.0.0-alpha.40](https://code.podlibre.org/podlibre/castopod/compare/v1.0.0-alpha.39...v1.0.0-alpha.40) (2021-03-19)

### Features

* **custom-rss:** add custom xml tag injection in rss feed for ❬channel❭ and ❬item❭ ([6ecdaad9](https://code.podlibre.org/podlibre/castopod/commit/6ecdaad911d06b7f7a2b7d24710968c7eb9118f6))