Disable USE_UNICODE_WRITER for Py3.11 (GH-4480)

Python 3.11 hid _PyLong_FormatAdvancedWriter and
_PyFloat_FormatAdvancedWriter. I've disabled USE_UNICODE_WRITER
for the moment but I suspect we want to find replacements in the longer term.

Cython/Utility/ModuleSetupCode.c

@@ -160,7 +160,9 @@
   #ifndef CYTHON_USE_UNICODE_INTERNALS
     #define CYTHON_USE_UNICODE_INTERNALS 1
   #endif
-  #if PY_VERSION_HEX < 0x030300F0
+  #if PY_VERSION_HEX < 0x030300F0 || PY_VERSION_HEX >= 0x030B00A2
+    // Python 3.11a2 hid _PyLong_FormatAdvancedWriter and _PyFloat_FormatAdvancedWriter
+    // therefore disable unicode writer until a better alternative appears
     #undef CYTHON_USE_UNICODE_WRITER
     #define CYTHON_USE_UNICODE_WRITER 0
   #elif !defined(CYTHON_USE_UNICODE_WRITER)