Error on send email with attachment

[azharmalik3]

Describe the bug

After the update from 1.15.3 to 1.16.3, I am getting errors using the Mailgun adapter when include the email attachments:

(UndefinedFunctionError) function Multipart.Part.file_content_field/5 is undefined or private\\n    (multipart 0.4.0) Multipart.Part.file_content_field(\\\"Evercam Dublin Office I--2024-Mar-28--22:46.jpg\\\", <<255, 216, 255, 224, 0, 16, 74, 70, 73, 70, 0, 1, 2, 0, 0, 1, 0, 1, 0, 0, 255, 254, 0, 16, 76, 97, 118, , 21, 24, ...>>, \\\"attachment\\\", [], [content_type: \\\"image/jpeg\\\"])

Steps to Reproduce the Bug or Issue

Easy to reproduce this error. Just include attachments.

Expected behavior

No response

Your reproducible example

No response

Screenshots or Videos

No response

Platform

• OTP: 24.0
• Elixir: 1.14.0

Additional context

We just downgraded swoosh to 1.15.3 it started working again. It means this error especially happened after rewriting multipart in 1.16.1