Automated e2e tests against different wordpress versions

[vernaillen]

Since upgrading WordPress to version 6.5 required a change in the WPNuxt graphql queries, it is clear that we might need to be able to easily test WPNuxt with different WordPress versions.
This allows us to detect breaking changes faster and assure backward compatibility.

The current docker-compose setup was created to be able to quickly spin up a local development environment, but can maybe be extended to spin up different test environment(s) with different wordpress version(s) in continuous integration.

[vernaillen]

idea: spin up the docker-compose environment in circleci: https://circleci.com/docs/docker-compose/

Can we define multiple docker-compose setups, one for each wordpress version? Place it all under "tests" folder?