build: set minimal php version to 8.1

.gitlab-ci.yml

app/Config/Fediverse.php

app/Controllers/EpisodeController.php

app/Controllers/WebmanifestController.php

app/Entities/Clip/VideoClip.php

app/Entities/Episode.php

app/Entities/Location.php

app/Entities/Podcast.php

app/Helpers/form_helper.php

app/Helpers/media_helper.php

app/Libraries/MediaClipper/VideoClipper.php

app/Libraries/Router.php

app/Models/EpisodeCommentModel.php

app/Models/PlatformModel.php

app/Views/Components/DropdownMenu.php

builds

composer.json

composer.lock

docker/production/app/Dockerfile

docs/src/ar/getting-started/install.md