fix addrOfMut warning

Summary:
Fixes the following warning by following the advice given:

```
warning: creating a mutable reference to mutable static is discouraged
  --> fbcode/eden/scm/lib/cpython-ext/src/bytesobject.rs:37:13
   |
37 |             &mut PyBytes_Type as *mut PyTypeObject,
   |             ^^^^^^^^^^^^^^^^^ mutable reference to mutable static
   |
   = note: for more information, see issue #114447 <rust-lang/rust#114447>
   = note: this will be a hard error in the 2024 edition
   = note: this mutable reference has lifetime `'static`, but if the static gets accessed (read or written) by any other means, or any other reference is created, then any further use of this mutable reference is Undefined Behavior
   = note: `#[warn(static_mut_refs)]` on by default
help: use `addr_of_mut!` instead to create a raw pointer
   |
37 |             addr_of_mut!(PyBytes_Type) as *mut PyTypeObject,
   |             ~~~~~~~~~~~~~            +

```

Reviewed By: quark-zju

Differential Revision: D65218834

fbshipit-source-id: 8298cdf8089b6d8516e0cb59a811b30465eb1f8c

eden/scm/lib/cpython-ext/src/bytesobject.rs

@@ -7,13 +7,13 @@
 
 use std::mem;
 use std::os::raw::c_char;
+use std::ptr::addr_of_mut;
 use std::slice;
 
 use cpython::PyObject as RustPyObject;
 use cpython::Python as RustPythonGILGuard;
 use ffi::PyBytes_Type;
 use ffi::PyObject;
-use ffi::PyTypeObject;
 use ffi::PyVarObject;
 use ffi::Py_hash_t;
 use ffi::Py_ssize_t;
@@ -34,7 +34,7 @@ struct PyBytesObject {
 pub fn allocate_pybytes(py: RustPythonGILGuard<'_>, size: usize) -> (RustPyObject, &mut [u8]) {
     unsafe {
         let ptr: *mut PyVarObject = _PyObject_NewVar(
-            &mut PyBytes_Type as *mut PyTypeObject,
+            addr_of_mut!(PyBytes_Type),
             (size + mem::size_of::<PyBytesObject>()) as Py_ssize_t,
         );
         let mut ptr: *mut PyObject = mem::transmute(ptr);