Add zig-libp2p to ~failing?

[dhuseby]

@MarcoPolo your minimal libp2p impl in zig is showing up with a bunch of failures: https://libp2p.io/status/transport/quic-v1/

There's three options and I wanted to get your take on them:

1. remove it from the test matrix altogether and add it to "dormant implementations" list
2. add it to the ~failing alias so it gets skipped in test runs that feed the dashboard
3. fix it

Which one would you prefer?