Describe the bug

When writing an empty case expression I'm used to writing the layout brackets {} explicitly to avoid confusion, but ormolu removes them.

To Reproduce

$ echo "case () of {}" | ormolu
case () of

Expected behavior

$ echo "case () of {}" | ormolu
case () of {}

Environment

• OS name + version: NixOS 21.05
• Version of the code:
  ormolu 0.1.4.1 UNKNOWN UNKNOWN
  using ghc-lib-parser 8.10.4.20210206
  (from nixpkgs)