We do not have this optional dependency packaged yet.

--- attrs-24.3.0/pyproject.toml.orig
+++ attrs-24.3.0/pyproject.toml
@@ -39,7 +39,6 @@
   # For regression test to ensure cloudpickle compat doesn't break.
   'cloudpickle; platform_python_implementation == "CPython"',
   "hypothesis",
-  "pympler",
   # 4.3.0 dropped last use of `convert`
   "pytest>=4.3.0",
   "pytest-xdist[psutil]",