We do not have this optional dependency packaged yet.

--- attrs-25.4.0/pyproject.toml.orig
+++ attrs-25.4.0/pyproject.toml
@@ -45,7 +45,6 @@
   # For regression test to ensure cloudpickle compat doesn't break.
   'cloudpickle; platform_python_implementation == "CPython"',
   "hypothesis",
-  "pympler",
   "pytest",
   "pytest-xdist[psutil]",
 ]