logging_json: fix RecursionError

Since Python 3.10, the use of 'threading.currentThread()' is deprecated
and generates a warning, and generating this warning log was in turn
entering in the `logging_json` mechanism, triggering an exception:

RecursionError: maximum recursion depth exceeded while calling a Python object

logging_json/json_log.py

@@ -26,7 +26,7 @@ def is_true(strval):
 class OdooJsonFormatter(jsonlogger.JsonFormatter):
     def add_fields(self, log_record, record, message_dict):
         record.pid = os.getpid()
-        record.dbname = getattr(threading.currentThread(), "dbname", "?")
+        record.dbname = getattr(threading.current_thread(), "dbname", "?")
         record.request_id = getattr(threading.current_thread(), "request_uuid", None)
         record.uid = getattr(threading.current_thread(), "uid", None)
         _super = super(OdooJsonFormatter, self)