PyPy 3.11 does not implement Py_TPFLAGS_MANAGED_DICT (#5508)

* PyPy 3.11 does not implement Py_TPFLAGS_MANAGED_DICT

* add a comment (from review)

* style: pre-commit fixes

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

Author: mattip

include/pybind11/detail/class.h

@@ -574,9 +574,9 @@ extern "C" inline int pybind11_clear(PyObject *self) {
 inline void enable_dynamic_attributes(PyHeapTypeObject *heap_type) {
     auto *type = &heap_type->ht_type;
     type->tp_flags |= Py_TPFLAGS_HAVE_GC;
-#if PY_VERSION_HEX < 0x030B0000
-    type->tp_dictoffset = type->tp_basicsize;           // place dict at the end
-    type->tp_basicsize += (ssize_t) sizeof(PyObject *); // and allocate enough space for it
+#if PY_VERSION_HEX < 0x030B0000 || defined(PYPY_VERSION) // For PyPy see PR #5508
+    type->tp_dictoffset = type->tp_basicsize;            // place dict at the end
+    type->tp_basicsize += (ssize_t) sizeof(PyObject *);  // and allocate enough space for it
 #else
     type->tp_flags |= Py_TPFLAGS_MANAGED_DICT;
 #endif