bpo-39481: Make os.DirEntry generic (GH-19415)

diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
index 4264bf1..57f1487 100644
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -12976,6 +12976,8 @@
     OS_DIRENTRY_STAT_METHODDEF
     OS_DIRENTRY_INODE_METHODDEF
     OS_DIRENTRY___FSPATH___METHODDEF
+    {"__class_getitem__",       (PyCFunction)Py_GenericAlias,
+    METH_O|METH_CLASS,          PyDoc_STR("See PEP 585")},
     {NULL}
 };