[experimental] fix Websocket 0-RTT header string

[teddysun]

Thanks & Merged

[sqwwqw5]

Thanks & Merged

I'm not exactly sure if it's gonna work though, I have no real coding experience, by looking at the code for hours this is what I come up with... It won't break anything for sure.

[sqwwqw5]

I do know the root cause is the header is not properly set, but I can't tell if it's caused by the strings getting overwritten here or if the path conversion doesn't happen at all, by guts I feel like it's the former scenario.