run fourmolu

Author: MaximilianAlgehed

.github/workflows/haskell-ci.yml

@@ -52,6 +52,8 @@ jobs:
           key: ${{ matrix.os }}-${{ matrix.ghc-version }}-${{ github.sha }}
           path: ~/.cabal/store
           restore-keys: ${{ matrix.os }}-${{ matrix.ghc-version }}-
+      - run: cabal install fourmolu-0.19.0.1
+      - run: fourmolu -c .
       - run: cabal build all
       - run: cabal test all
       - run: cabal haddock all