Update IPv6 Address of watch.ocaml.org. It is currently unavailable over IPv6

[mtelvers]

@avsm Please can you update the IPv6 address for watch.ocaml.org.

The new AAAA record should be 2001:bc8:4748:202::1

This is a recurrence of #75. I updated the OS from Ubuntu 20.04 to 22.04 yesterday, and while I would not expect this to change the IPv6 address, it seems to have done so.

[shonfeder]

From conversation with Mark: it seems like this may be a configuration error on Scaleway's side, as we would expect this IP address to be static. If possible, it would be helpful to get them to fix this, or at least confirm that they cannot. If the latter, perhaps we can figure out a workaround. Otherwise, it seems we risk having to redo this work every time the machines need to be upgraded.

afaiu, my ability to help here is limited due to sensible permissions and access controls. But I'd be very happy to do whatever I can to address the root cause here, so please let me know if there's something I can do.

[shonfeder]

We got another alert on this today:

@mtelvers testing: Error: Command "curl" "-L" "--resolve" "watch.ocaml.org:443:[2001:bc8:47e4:202::1]"
"https://watch.ocaml.org/" exited with status 7

confirmed by https://www.ssllabs.com/ssltest/analyze.html?d=watch.ocaml.org