Stable version v1.7.3

• Usability:
  • Not to import custom handlers (StreamHandlerWithBuffer, TelegramHandler, etc) if they are not used in any logger.
  • TelegramHandler:
    • Better network error handling.
    • Added grouping_interval to group many log messages that are within the same x seconds interval into one before sending.
      This reduces the number of times it sends messages to the Telegram server and helps to avoid Http-429 error.