Bump cabal version to 2.4

* This is the newest cabal version supported by stack
* Remove warning about missing Default-language field
* Remove warning regarding the License field

Author: lukasz-golebiewski

stylish-haskell.cabal

@@ -1,15 +1,15 @@
+Cabal-version: 2.4
 Name:          stylish-haskell
 Version:       0.12.0.0
 Synopsis:      Haskell code prettifier
 Homepage:      https://github.com/jaspervdj/stylish-haskell
-License:       BSD3
+License:       BSD-3-Clause
 License-file:  LICENSE
 Author:        Jasper Van der Jeugt <m@jaspervdj.be>
 Maintainer:    Jasper Van der Jeugt <m@jaspervdj.be>
 Copyright:     2012 Jasper Van der Jeugt
 Category:      Language
 Build-type:    Simple
-Cabal-version: >= 1.10
 
 Description:
     A Haskell code prettifier. For more information, see: