Implementing test parallelisation

[doublevcodes]

What we want

We would like to consider parallelising the execution of tests.

How do we do it

This can be done with pytest-xdist

What problems do we face

• We might need to change how the database is created. For example, creating a new database for each worker

[D0rs4n]

My proposal is to just simply create test databases using worker ids (see the docs) I have already added the logic to my PR that could be modified.
(We're talking about a fairly easy modification)