ignore echo messages from facebook

[aristidednd]

According to Facebook Messenger API documentation https://developers.facebook.com/docs/messenger-platform/reference/webhook-events/message-echoes/?locale=en_En, an echo message is also triggered for image, video, file, and audio attachments. These changes ignore those echo messages.

Proposed changes:

• Ignore echo messages related to file, audio, video, and image attachments from Facebook

Status (please check what you already did):

• [ ] added some tests for the functionality
• [ ] updated the documentation
• [ ] updated the changelog (please check changelog for instructions)
• [ ] reformat files using black (please check Readme for instructions)

[CLAassistant]

All committers have signed the CLA.

[stale[bot]]

This PR has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[Tung8787]

Tui chả hiểu hì :)))