Bridges do not build on latest go (1.21)

[robvanmieghem]

While publishing 1.5.2:

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

This should have been detected during a CI build before publishing the release