Revert manual installation of `happy`
Revert manual installation of `happy`

It does not fixed the issue we have had...

input-output-hk/cardano-sl,input-output-hk/cardano-sl,input-output-hk/cardano-sl-explorer,input-output-hk/pos-haskell-prototype,input-output-hk/cardano-sl,input-output-hk/pos-haskell-prototype,input-output-hk/cardano-sl-explorer,input-output-hk/pos-haskell-prototype,input-output-hk/cardano-sl-explorer,input-output-hk/cardano-sl