refactor migration queries to use forge functions

- use codeigniter4/tasks project to handle cron tasks
- use yassinedoghri/podcast-feed project to parse feeds for imports

update composer dependencies to latest

refs #321

After install, the redirect condition is kept even though it would never be triggered again.

closes #225

closes #222

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

closes #193

update composer dependencies to latest

Some episodes could not be unpublished because of out of range error when removing posts.

fixes #233

- remove delete_at field + soft delete for media and pages
- update CodeIgniter4 to 4.2.0 + update all starter files
- explicitly use builder() when creating queries from model 

- update CI4 to v4.1.9's stable production package
- update php and js dependencies to latest

remove cache when adding comment and replies as well

fixes #169

- rename podlibre to adaures
- rename castopod-host to castopod
- simplify README and redirect to docs site
- move INSTALL and UPDATE docs
- add new gitlabci pipeline to deploy docs
- upgrade node to v16 in Dockerfile

fixes #164