Remove code inside 'PYPY_VERSION_NUM < 0x06000000' preprocessor if branch

Author: YannickJadoul

include/pybind11/detail/class.h

@@ -475,11 +475,6 @@ extern "C" inline int pybind11_clear(PyObject *self) {
 /// Give instances of this type a `__dict__` and opt into garbage collection.
 inline void enable_dynamic_attributes(PyHeapTypeObject *heap_type) {
     auto type = &heap_type->ht_type;
-#if defined(PYPY_VERSION) && (PYPY_VERSION_NUM < 0x06000000)
-    pybind11_fail(std::string(type->tp_name) + ": dynamic attributes are "
-                                               "currently not supported in "
-                                               "conjunction with PyPy!");
-#endif
     type->tp_flags |= Py_TPFLAGS_HAVE_GC;
     type->tp_dictoffset = type->tp_basicsize; // place dict at the end
     type->tp_basicsize += (ssize_t)sizeof(PyObject *); // and allocate enough space for it