beancount: disable testing

Tests weren't actually executed before.

pkgs/applications/office/beancount/default.nix

@@ -13,8 +13,10 @@ pythonPackages.buildPythonApplication rec {
 
   buildInputs = with pythonPackages; [ nose ];
 
+  # Automatic tests cannot be run because it needs to import some local modules for tests.
+  doCheck = false;
   checkPhase = ''
-    nosetests $out
+    nosetests
   '';
 
   propagatedBuildInputs = with pythonPackages; [