Set upper bounds in our build-depends cabal fields

We decided to use PVP to version our packages (except we'll not be particularly careful about upstream orphan instances). That strongly implies/requires that we are specifying upper bounds in our cabal files.

This task is to add upper bounds to all of our cabal files.

For this bootstrap, we should just use the current MAJOR(.MAJOR).MINOR.* bounds (or cabal's <=^ caret operator) for whatever MAJOR and MINOR the cabal solver currently chooses for our dependencies.