Changing minor references (name of file, location of image, non-deprecated class name)

What's Changed

• Rename docker-compose.yml to compose.yaml by @briskt in #7
• Switch compose to php8 from GHCR by @devon-sil in #8
• [ITSESUP-109] Update README.md to use ::class instead of ::className() by @mtompset in #9

New Contributors

• @briskt made their first contribution in #7
• @devon-sil made their first contribution in #8
• @mtompset made their first contribution in #9

Full Changelog: 1.2.1...1.2.2