fix: discrepancy with chrome handling of whitespace in header

[Llandy3d]

Description

Disable the validate_inbound_headers option in the proxy, it should protect from request smuggling but it shouldn't be an issue for the majority of our use cases. It causes issues when receiving whitespace in headers.

issue:

• Support Request: 502 Bad Gateway Error in K6 Studio #887

reference:

• HTTP/2 protocol error: Received header value surrounded by whitespace mitmproxy/mitmproxy#4836 (comment)
• HTTP/2 protocol error: Received header value surrounded by whitespace b'1.mxp _dca ' mitmproxy/mitmproxy#5480

How to Test

Checklist

• I have performed a self-review of my code.
• I have added tests for my changes.
• I have commented on my code, particularly in hard-to-understand areas.

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