Support Unity attachments

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Description

I am using the Unity Sentry client, which allows me to send screenshot attachments (AFAIK a jpg). When I try this with GlitchTip the envelope is rejected with the following error message from my sentry client:

Sentry: (Error) Sentry rejected the envelope 19aa02662e2d41f2817de2e974ac19d5. Status code: BadRequest. Error detail: JSON parse error - 'utf-8' codec can't decode byte 0xff in position 0: invalid start byte. Error causes: .

Are attachments in general already handled by GlitchTip ( https://docs.sentry.io/platforms/unity/enriching-events/attachments/ ) ? If yes: What kind of attachments are allowed and would it be possible to allow all kinds?

Proposed Solution(s)

GlitchTip should be able to handle all kinds of event attachments.