gh-137058: Update C23 standard version check in pyport.h

Author: abdoulrasheed

Include/pyport.h

@@ -50,7 +50,7 @@
 // to prevent C++ compiler warnings. On C23 and newer and on C++11 and newer,
 // _Py_NULL is defined as nullptr.
 #if !defined(_MSC_VER) && \
-    ((defined (__STDC_VERSION__) && __STDC_VERSION__ > 201710L) \
+    ((defined (__STDC_VERSION__) && __STDC_VERSION__ >= 202311L) \
         || (defined(__cplusplus) && __cplusplus >= 201103))
 #  define _Py_NULL nullptr
 #else