Update testing EDSL example
Clarification and motivation
This is basically a re-vamped version of #166 (closed)
Our EDSL testing example is using an old LTS and morley
version.
This should be started after #301 (closed) which is already in progress in order to avoid it to be immediately outdated again.
Acceptance criteria
examples/EDSL
uses the latest morley
from Hackage and the latest resolver we are using in the repo. docs/testingEDSL.md
is updated accordingly.