hydra: berlin: Allow HTTP to any IP address.

I wanted to keep this minimal.  It didn't work: Wireguard clients use
10.0.0.0/8 IPs directly as well.

* hydra/nginx/berlin.scm (%berlin-servers): Match anything ending in a
digit, which, until the gTLD crowd goes truly bonkers, is an IP address.
And if it's not, the request wouldn't reach us anyway, right?

Reported by Ludovic Courtès <ludo@gnu.org>.

hydra/nginx/berlin.scm

@@ -820,7 +820,7 @@ PUBLISH-URL."
     (listen '("80"))
     (server-name '("ci.guix.gnu.org"
 		   ;; <https://logs.guix.gnu.org/guix/2021-11-20.log#155427>
-		   "141.80.167.131"))
+		   "~[0-9]$"))
     (locations (berlin-locations %publish-url))
     (raw-content
      (list