nginx: Don't look up localhost via DNS

This results in occasional failure to resolve proxies because it turns
into [::1] for IPv6 reasons.

We hard-code the IPv4 address since the containers don't currently
support IPv6.

configuration/default.nix

@@ -61,7 +61,7 @@
         {
           forceSSL = true;
           enableACME = true;
-          locations."/" = { proxyPass = "http://localhost:${toString port}"; };
+          locations."/" = { proxyPass = "http://127.0.0.1:${toString port}"; };
         } // extra;
     in {
       "tlater.net" = host 3002 { serverAliases = [ "www.tlater.net" ]; };