gitAndTools.gitRemoteGcrypt: No need for rst2man patch anymore

pkgs/applications/version-management/git-and-tools/git-remote-gcrypt/default.nix

···
 
   outputs = [ "out" "man" ];
 
-  buildInputs = [ docutils makeWrapper ];
-
-  # The install.sh script expects rst2man, but here it's named rst2man.py
-  patchPhase = ''
-    sed -i 's/rst2man/rst2man.py/g' install.sh
-  '';
+  nativeBuildInputs = [ docutils makeWrapper ];
 
   installPhase = ''
     prefix="$out" ./install.sh