fix: update to_json ffi

src/common/json.c

@@ -17,8 +17,8 @@ uint8_t is_json_suffix(const char *file_name) { // whether file name end with `.
     return FALSE;
 }
 
-char* to_json(const char *content) { // convert JSON / TOML / YAML to json format (if failed -> return NULL)
-    const char *json_string = to_json_rust(content); // convert to json format
+char* to_json(const char *content) { // convert JSON / TOML / YAML to json format (failed -> NULL)
+    const char *json_string = to_json_ffi(content); // convert to json format
     char *json_content = strdup(json_string); // load string into owner heap
     free_rust_string(json_string); // free rust string
     if (strlen(json_content) == 0) { // empty string -> convert error
@@ -30,6 +30,7 @@ char* to_json(const char *content) { // convert JSON / TOML / YAML to json forma
     return json_content;
 }
 
+
 cJSON* json_field_get(cJSON *entry, const char *key) { // fetch key from json map (create when key not exist)
     cJSON *sub = entry->child;
     while (sub != NULL) { // traverse all keys