[BUG] Scripting: Get warning when making a multipart request

Description

The Script will show this Warning note in the Console if the request has multipart body.

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09:39:01.566: [onRequest] with Request ID=17
https://httpbin.proxyman.app/post?action=form
❌ Error: Missing Content-Type Header. Attempt to guess the Content-Type from the body!
09:39:01.582 onRequest() is executed!

Steps to Reproduce

1. Create a Script for some requests
2. Make a multipart request

Current Behavior

• Get error note in the console log
• Even though the request is called successfully

Expected Behavior

• Should now show this error because there is the Content-Type header in the Request
• Multipart Request should work with the Script