cleanup whitespace and commas

* [] is now [ ]
* {} is now { }
* commas in arglists go at end of line not beginning

In short, I ran the whole thing through nixfmt-rfc-style but only
accepted about 30% of its changes. I might grow accustomed to more
of it over time

pkgs/fennel/default.nix

@@ -1,7 +1,7 @@
 {
-  stdenv
-, lua
-, fetchFromSourcehut
+  stdenv,
+  lua,
+  fetchFromSourcehut,
 }:
 let pname =  "fennel";
 in stdenv.mkDerivation {