Since CI4 v4.2.8, the actor route is not retrieved anymore, this prevents users from creating a
podcast.

remove validate_url custom validator and replace with CI4's valid_url_strict

--> Having a URL with spaces in the beginning or end would cause the platform to be deleted

set the right permissions for episode's publication date edit

fixes #249

closes #225

+ update phpstan and rector configs

closes #222

This allows podcasters to reorganize their published episodes as they see fit

closes #97

closes #247

- clear podcast cache when setting subscription link
- update and add missing translation keys

closes #193