add a replacement API for PyCObject, PyCapsule #5630

All stdlib modules with C-APIs now use this.

Patch by Larry Hastings
diff --git a/Modules/pyexpat.c b/Modules/pyexpat.c
index a968e52..7a862c0 100644
--- a/Modules/pyexpat.c
+++ b/Modules/pyexpat.c
@@ -1987,8 +1987,8 @@
     capi.SetUnknownEncodingHandler = XML_SetUnknownEncodingHandler;
     capi.SetUserData = XML_SetUserData;
     
-    /* export as cobject */
-    capi_object = PyCObject_FromVoidPtr(&capi, NULL);
+    /* export using capsule */
+    capi_object = PyCapsule_New(&capi, PyExpat_CAPSULE_NAME, NULL);
     if (capi_object)
         PyModule_AddObject(m, "expat_CAPI", capi_object);
     return m;