Resolve symbol errors with Python 3.12

    Symbols missing in /opt/hostedtoolcache/Python/3.12.4/x64/lib/libpython3.12.so:
    PyCode_New
    PyCode_NewWithPosOnlyArgs
    PyUnicode_AsUnicode
    PyUnicode_AsUnicodeAndSize
    PyUnicode_FromUnicode
    _Py_GetAllocatedBlocks
    _Py_PackageContext

Python 3.12/3.11 renamed/deprecated some APIs. Update code to skip them.
This affects `linux (ubuntu-latest, 3.12, nightly)` CI.

Author: quark-zju

Diff for: python3-sys/src/code.rs

@@ -152,6 +152,7 @@ pub const CO_MAXBLOCKS: usize = 20;
 extern "C" {
     pub static mut PyCode_Type: PyTypeObject;
 
+    #[cfg_attr(Py_3_12, link_name = "PyUnstable_Code_New")]
     pub fn PyCode_New(
         argcount: c_int,
         kwonlyargcount: c_int,
@@ -175,6 +176,7 @@ extern "C" {
     ) -> *mut PyCodeObject;
 
     #[cfg(Py_3_8)]
+    #[cfg_attr(Py_3_12, link_name = "PyUnstable_Code_NewWithPosOnlyArgs")]
     pub fn PyCode_NewWithPosOnlyArgs(
         argcount: c_int,
         posonlyargcount: c_int,

Diff for: python3-sys/src/modsupport.rs

@@ -133,7 +133,7 @@ pub unsafe fn PyModule_FromDefAndSpec(def: *mut PyModuleDef, spec: *mut PyObject
     )
 }
 
-#[cfg(not(Py_LIMITED_API))]
+#[cfg(all(not(Py_LIMITED_API), not(Py_3_12)))]
 #[cfg_attr(windows, link(name = "pythonXY"))]
 extern "C" {
     pub static mut _Py_PackageContext: *const c_char;

Diff for: python3-sys/src/objimpl.rs

@@ -21,7 +21,7 @@ extern "C" {
     #[cfg(all(py_sys_config = "Py_DEBUG", not(Py_3_4)))]
     pub fn _PyObject_DebugFree(arg1: *mut c_void);
 
-    #[cfg(all(not(Py_LIMITED_API), Py_3_4))]
+    #[cfg(all(not(Py_LIMITED_API), Py_3_4, not(Py_3_11)))]
     pub fn _Py_GetAllocatedBlocks() -> Py_ssize_t;
     pub fn PyObject_Init(arg1: *mut PyObject, arg2: *mut PyTypeObject) -> *mut PyObject;
     pub fn PyObject_InitVar(

Diff for: python3-sys/src/unicodeobject.rs

@@ -52,7 +52,7 @@ extern "C" {
         length: Py_ssize_t,
         fill_char: Py_UCS4,
     ) -> Py_ssize_t;
-    #[cfg(not(Py_LIMITED_API))]
+    #[cfg(all(not(Py_LIMITED_API), not(Py_3_12)))]
     #[deprecated(since = "0.2.1", note = "Deprecated since Python 3.3 / PEP 393")]
     pub fn PyUnicode_FromUnicode(u: *const Py_UNICODE, size: Py_ssize_t) -> *mut PyObject;
 
@@ -78,10 +78,10 @@ extern "C" {
         copy_null: c_int,
     ) -> *mut Py_UCS4;
     pub fn PyUnicode_AsUCS4Copy(unicode: *mut PyObject) -> *mut Py_UCS4;
-    #[cfg(not(Py_LIMITED_API))]
+    #[cfg(all(not(Py_LIMITED_API), not(Py_3_12)))]
     #[deprecated(since = "0.2.1", note = "Deprecated since Python 3.3 / PEP 393")]
     pub fn PyUnicode_AsUnicode(unicode: *mut PyObject) -> *mut Py_UNICODE;
-    #[cfg(not(Py_LIMITED_API))]
+    #[cfg(all(not(Py_LIMITED_API), not(Py_3_12)))]
     #[deprecated(since = "0.2.1", note = "Deprecated since Python 3.3 / PEP 393")]
     pub fn PyUnicode_AsUnicodeAndSize(
         unicode: *mut PyObject,