gh-133644: remove deprecated PyImport_ImportModuleNoBlock (#133655)

Python/import.c

@@ -3434,8 +3434,10 @@ PyImport_ImportModule(const char *name)
  * ImportError instead of blocking.
  *
  * Returns the module object with incremented ref count.
+ *
+ * Removed in 3.15, but kept for stable ABI compatibility.
  */
-PyObject *
+PyAPI_FUNC(PyObject *)
 PyImport_ImportModuleNoBlock(const char *name)
 {
     if (PyErr_WarnEx(PyExc_DeprecationWarning,