use new value for SETTINGS_H3_DATAGRAM (according to RFC9297)

[Tantalor93]

Hello, while using the quic-go library I noticed that according to the RFC9297 the correct value for settingsDatagram is 0x33 (also mentioned here), the value 0xffd277 was used in draft. I gave it a shot and tried to fix it myself, let me know if I am missing something 🙂. Otherwise thanks for the great work on this project!

RFC9297

An endpoint can indicate to its peer that it is willing to receive HTTP/3 Datagrams by sending the SETTINGS_H3_DATAGRAM (0x33) setting with a value of 1.

old draft IANA consideration:

HTTP/3 SETTINGS Parameter
This document will request IANA to register the following entry in the "HTTP/3 Settings" registry:
Value:
0xffd277 (note that this will switch to a lower value before publication)
Setting Name:
H3_DATAGRAM

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[marten-seemann]

We'll need to test if this breaks WebTransport support with Chrome and Firefox.

[dongcarl]

Just for reference, the new standardized value has been part of the web-platform-tests suite since 3 months ago: web-platform-tests/wpt#39201.

[marten-seemann]

Duplicate of #3588.