use new Cabal test interface

```
% cabal configure
...
Setup.hs:5:68:
Warning: In the use of `runTests'
(imported from Distribution.Simple, but defined in Distribution.Simple.UserHooks):
Deprecated: "Please use the new testing interface instead!"
```

Start by inspecting Setup.hs and running cabal configure to reproduce the deprecation warning. Read Cabal's current testing interface documentation and compare it with the runTests' usage reported in the warning. Done means the project uses the new test interface and cabal configure no longer reports this deprecation.

Written by the indexing model from the issue text.