quic: don't support draft versions

[marten-seemann]

rust-libp2p's QUIC implementation currently supports a long list of versions (obtained by eliciting a Version Negotiation packet): [v1 draft-29 0xff00001e 0xff00001f 0xff000020 0xff000021 0xff000022]

The 0xff... versions are QUIC draft versions (see https://github.com/quicwg/base-drafts/wiki/QUIC-Versions).

We've never deployed any version other than v1 and draft-29 in libp2p, so there's no reason to enable support for these versions.

Overarching tracking issue #2883.

[mxinden]

Thank you @marten-seemann for raising and documenting this.

I suggest we drop support for draft-29 along with all other draft versions. See same deprecation on the go-libp2p side libp2p/go-libp2p#2369.

Steps:

1. Deprecate libp2p_quic::Config::support_draft_29.
2. Remove libp2p_quic::Config::support_draft_29 and always set endpoint_config.supported_versions to vec![1].
   

   rust-libp2p/transports/quic/src/config.rs

   Lines 131 to 134 in 915c4ad

   	let mut endpoint_config = quinn::EndpointConfig::default();
   	if !support_draft_29 {
   	endpoint_config.supported_versions(vec![1]);
   	}

Contributions from the community would be very welcome. Please post here in case you want to pick this up.

[erwin-kok]

@mxinden @marten-seemann I would like to work on this, please assign to me.

[thomaseizinger]

@mxinden @marten-seemann I would like to work on this, please assign to me.

Done! Thank you for your help :)