reduce :pedantic? to :warn if :abort is specified.

[xsc]

Reason: when checking if a dependency would suit an existing project (e.g. my project has a map of data somewhere and I want to serialize that data to JSON but want to try out different libraries) dependency conflicts will prevent the REPL from starting if pedantic? is set to :abort.

The user should be able to add the dependency, try it out and handle any such conflicts at a later point in time which is why this PR will reduce the :pedantic? level to :warn if it is :abort.