diff-so-fancy: add HEAD (#15729)

Author: jeffbyrnes

Formula/diff-so-fancy.rb

@@ -3,6 +3,7 @@ class DiffSoFancy < Formula
   homepage "https://github.com/so-fancy/diff-so-fancy"
   url "https://github.com/so-fancy/diff-so-fancy/archive/v1.1.1.tar.gz"
   sha256 "9505fa729e1e5a4e3ca9af22db3c07342e8544f5151c73ccf05c6b3b3f2e835f"
+  head "https://github.com/so-fancy/diff-so-fancy.git", :branch => "next"
 
   bottle :unneeded