cloudflared: Doesn't build with Go 1.21

Seems to require a custom go-quic version which doesn't support Go 1.21 yet. From the build log:

vendor/github.com/quic-go/quic-go/internal/qtls/go121.go:5:13: cannot use "The version of quic-go you're using can't be built on Go 1.21 yet. For more details, please see https://github.com/quic-go/quic-go/wiki/quic-go-and-Go-versions." (untyped string constant "The version of quic-go you're using can't be built on Go 1.21 yet. F...) as int value in variable declaration

Therefore disabled in 29723fb6