refactor: update code base to php 8 and set phpstan lvl to 6

app/Entities/Category.php

app/Entities/Credit.php

app/Entities/Episode.php

app/Entities/EpisodePerson.php

app/Entities/Image.php

app/Entities/Note.php

app/Entities/Page.php

app/Entities/Person.php

app/Entities/Podcast.php

app/Entities/PodcastPerson.php

app/Filters/PermissionFilter.php

app/Helpers/auth_helper.php

app/Helpers/breadcrumb_helper.php

app/Helpers/components_helper.php

app/Helpers/form_helper.php

app/Helpers/id3_helper.php

app/Helpers/location_helper.php

app/Helpers/media_helper.php

app/Helpers/misc_helper.php

app/Helpers/persons_helper.php