* PHP 8 support, test workflow syntax
* Try using a custom data structure in the workflow
* Try using matrix include
* Default PHP target
* single include
* fix composer package name
* [WIP] Try using dev-master for valuestore
* Update spatie/valuestore constraint to be stable
Changed the dockerfile to use the official Docker php image and installed
the pcov extension instead of xdebug for code coverage.
Also updated the docker-compose file to make the main 'test' service not start up
before all the DB containers are running ok.
