[3.14] Document Py_AddPendingCall() change with subinterpreters in 3.12 (GH-139117) (#139118)

Co-authored-by: Peter Bierma <[email protected]>

Author: miss-islington

Doc/c-api/init.rst

@@ -2002,6 +2002,10 @@ pointer and a void pointer argument.
       called from the main interpreter. Each subinterpreter now has its own
       list of scheduled calls.
 
+   .. versionchanged:: 3.12
+      This function now always schedules *func* to be run in the main
+      interpreter.
+
 .. _profiling:
 
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