hamster: fix install

* Tell the build system where it can install Python files, with the
  PYTHONDIR environment variable. Without this it tries to install to
  the existing python3 store path, which fails:

    waflib.Errors.WafError: Could not create the directory /nix/store/HASH-python3-VERSION/lib/pythonX.Y/site-packages/hamster

* Add setuptools as runtime dependency to prevent this fatal runtime
  error since Python 3.12:

    ModuleNotFoundError: No module named 'distutils'

pkgs/applications/misc/hamster/default.nix

@@ -35,9 +35,12 @@ python3Packages.buildPythonApplication rec {
     pygobject3
     pycairo
     pyxdg
+    setuptools
     dbus-python
   ];
 
+  PYTHONDIR = "${placeholder "out"}/${python3Packages.python.sitePackages}";
+
   dontWrapGApps = true;
 
   # Arguments to be passed to `makeWrapper`, only used by buildPython*