frogmouth: implement a more targeted patch for switching from xdg to xdg-base-dirs

Thanks to @eclairevoyant for suggesting something more minimal.

pkgs/tools/text/frogmouth/default.nix

@@ -15,7 +15,12 @@ python3.pkgs.buildPythonApplication rec {
     hash = "sha256-TMCeIwMEoNDQV9iue4XrdYQMmwofXDvdMMLTZKILQ9Q=";
   };
 
-  patches = [ ./use-xdg-base-dirs.patch ];
+  # Per <https://github.com/srstevenson/xdg-base-dirs/tree/6.0.0#xdg-base-dirs>, the package is
+  # renamed from `xdg` to `xdg_base_dirs`, but upstream isn't amenable to performing that rename.
+  # See <https://github.com/Textualize/frogmouth/pull/59>. So this is a minimal fix.
+  postUnpack = ''
+    sed -i -e "s,from xdg import,from xdg_base_dirs import," $sourceRoot/frogmouth/data/{config,data_directory}.py
+  '';
 
   nativeBuildInputs = [
     python3.pkgs.poetry-core