scalafmt: use setJavaClassPath, drop jdk dep

pkgs/development/tools/scalafmt/default.nix

···
-{ lib, stdenv, jdk, jre, coursier, makeWrapper }:
+{ lib, stdenv, jre, coursier, makeWrapper, setJavaClassPath }:
 
 let
   baseName = "scalafmt";
···
   pname = baseName;
   inherit version;
 
-  nativeBuildInputs = [ makeWrapper ];
-  buildInputs = [ jdk deps ];
+  nativeBuildInputs = [ makeWrapper setJavaClassPath ];
+  buildInputs = [ deps ];
 
   dontUnpack = true;