Fix queue.SimpleQueue.__sizeof__() to account for buffer

Fixes #140025

The __sizeof__() method for queue.SimpleQueue previously ignored
the underlying RingBuf data structure, only returning the basic
object size.

Now properly accounts for the dynamically allocated items array
in the RingBuf, which grows with the queue capacity:
- Returns base object size + (items_cap * sizeof(PyObject*))

This gives accurate memory usage for SimpleQueue instances.

Author: ayushm98

Modules/_queuemodule.c

@@ -524,6 +524,15 @@ queue_free(void *m)
     (void)queue_clear((PyObject *)m);
 }
 
+static PyObject *
+simplequeue_sizeof(simplequeueobject *self, PyObject *Py_UNUSED(ignored))
+{
+    Py_ssize_t res = _PyObject_SIZE(Py_TYPE(self));
+    // Add size of the RingBuf items array
+    res += self->buf.items_cap * sizeof(PyObject *);
+    return PyLong_FromSsize_t(res);
+}
+
 #include "clinic/_queuemodule.c.h"
 
 
@@ -534,6 +543,8 @@ static PyMethodDef simplequeue_methods[] = {
     _QUEUE_SIMPLEQUEUE_PUT_METHODDEF
     _QUEUE_SIMPLEQUEUE_PUT_NOWAIT_METHODDEF
     _QUEUE_SIMPLEQUEUE_QSIZE_METHODDEF
+    {"__sizeof__",           (PyCFunction)simplequeue_sizeof,
+    METH_NOARGS,             PyDoc_STR("Return the size of the SimpleQueue in memory, in bytes.")},
     {"__class_getitem__",    Py_GenericAlias,
     METH_O|METH_CLASS,       PyDoc_STR("See PEP 585")},
     {NULL,           NULL}              /* sentinel */