Prevent a TypeError: 'NoneType' object is not callable when ``shu…

…til_rmtree`` is called without an ``onexc`` parameter on Python<=3.11

newsfragments/xxxx.bugfix.rst

@@ -0,0 +1 @@
+Prevent a ``TypeError: 'NoneType' object is not callable`` when ``shutil_rmtree`` is called without an ``onexc`` parameter on Python<=3.11 -- by :user:`Avasam`

setuptools/compat/py311.py

@@ -1,12 +1,16 @@
+from __future__ import annotations
+
 import sys
 import shutil
 
 
-def shutil_rmtree(path, ignore_errors=False, onexc=None):
+def shutil_rmtree(
+    path, ignore_errors: bool = False, onexc: shutil._OnExcCallback | None = None
+) -> None:
     if sys.version_info >= (3, 12):
         return shutil.rmtree(path, ignore_errors, onexc=onexc)
 
     def _handler(fn, path, excinfo):
-        return onexc(fn, path, excinfo[1])
+        return onexc(fn, path, excinfo[1]) if onexc else None
 
     return shutil.rmtree(path, ignore_errors, onerror=_handler)