fix docs more

Author: maksbotan

doc/tutorial/Server.lhs

@@ -47,7 +47,6 @@ import System.Directory
 import Text.Blaze
 import Text.Blaze.Html.Renderer.Utf8
 import Servant.Types.SourceT (source)
-import qualified Data.Aeson.Parser
 import qualified Text.Blaze.Html
 ```