gh-146244: Fix initconfig.c SET_ITEM macro leaks dict on expression failure (GH-146246)

(cherry picked from commit 9343518)

Co-authored-by: Wulian233 <1055917385@qq.com>

Author: Wulian233

Python/initconfig.c

@@ -502,7 +502,7 @@ _Py_COMP_DIAG_IGNORE_DEPR_DECLS
         do { \
             obj = (EXPR); \
             if (obj == NULL) { \
-                return NULL; \
+                goto fail; \
             } \
             int res = PyDict_SetItemString(dict, (KEY), obj); \
             Py_DECREF(obj); \