Replacing return with pure unindents

Input file:
```hs
foo =
  return $ case x of
    Just a -> a + 1
    Nothing -> 0
```
After `hlint --refactor --with-group=future`:
```hs
foo =
  pure $ case x of
  Just a -> a + 1
  Nothing -> 0
```
I'm using `apply-refact-0.9.3.0` because our codebase is still on GHC 9.0, but I don't see any PRs fixing this in 0.10