Add filename of attachment

[wgresshoff]

❤️ Thank you for your contribution!

Description

Please describe briefly your pull request.

Currently there is no possibility to set the name of an attachment. This PR will add the possibility.

Checklist

Ticks in all boxes and 🟢 on all GitHub actions status checks are required to merge:

• I'm aware of the code of conduct.
• I've created logical separate commits and followed the commit message format.
• I've added relevant test cases.
• I've added relevant documentation.
• I've marked translation strings.
• I've identified the copyright holder(s) and updated copyright headers for touched files (>15 lines contributions).
• I've NOT included third-party code (copy/pasted source code or new dependencies).
  • If you have added third-party code (copy/pasted or new dependencies), please reach out to an architect.

Frontend

• I've followed the CSS/JS and React guidelines.
• I've followed the web accessibility guidelines.
• I've followed the user interface guidelines.

Reminder

By using GitHub, you have already agreed to the GitHub’s Terms of Service including that:

1. You license your contribution under the same terms as the current repository’s license.
2. You agree that you have the right to license your contribution under the current repository’s license.

[ntarocco]

Is None an accepted value by msg.attach for the filename?

Suggested change

	filename = None
	if "filename" in attachment:
	filename = attachment.get("filename")
	filename = attachment.get("filename")

[wgresshoff]

Yes, None is accepted. But if you just call attachment.get("filename") and the key doesn't exist a KeyError will be raised.