chore: upgrade docs to docker compose v2

[SethFalco]

Topic and Scope

Upgrades instructions and the local test runner to use Docker Compose v2 instead of Docker Compose.

Docker Compose v2 has been out for some time, and Docker Compose v1 (docker-compose) no longer receives updates.

From July 2023 Compose V1 stopped receiving updates. It’s also no longer available in new releases of Docker Desktop.

— https://docs.docker.com/compose/

I think it makes sense to push the documentation and commands over to the v2 equivalents now, since this is what most engineers should have installed now.

Concerns/issues

I have only tested this locally. I'm not sure if this will work as-is on CI or if more needs to be done.

It's also worth considering if a significant portion of maintainers/contributors cannot upgrade to Docker Compose v2 for some reason? 🤔 (I can't think of one, but I'm just wary as I don't know why this repository was still using docker-compose instead of docker compose.)

A similar proposal was made for nextcloud-docker-dev, which looks like it will be merged soon too:

• Changed docker-compose -> docker compose juliusknorr/nextcloud-docker-dev#209

Formal requirements

There are some formal requirements that should be satisfied. Please mark those by checking the corresponding box.

• I did check that the app can still be opened and does not throw any browser logs
• I created tests for newly added PHP code (check this if no PHP changes were made)
• I updated the OpenAPI specs and added an entry to the API changelog (check if API was not modified)
• I notified the matrix channel if I introduced an API change

[github-actions]

Test Results

     27 files  1 233 suites   7m 9s ⏱️
   498 tests    498 ✔️ 0 💤 0 ❌
4 482 runs  4 481 ✔️ 1 💤 0 ❌

Results for commit 8b6bdd0.

♻️ This comment has been updated with latest results.