fix: update compose submodule to pick up backup network fix

The backup_stack.service was failing because the deployed compose.yml
still had backup_net declared as external: true, but the network was
never created externally.

PR #45 on the compose repo (d7449e9) already fixed this by changing
to driver: bridge, but the infra submodule was still pinned to a
pre-fix commit.

This updates assets/compose to d7449e9 so the next nixos-rebuild
switch deploys the fix.

lib/keys.nix

@@ -9,10 +9,6 @@
     ai-worker = {
       main = "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIAXeGtPPcsP2IYRQNvII41NVWhJsarEk8c4qxs/a5sXf";
     };
-
-    hermes_agent = {
-      age = "age178ypgaxn3fldh2aeqz37ncpk7jrplaxacrca8kkcycre3ahjef4s2dp3rp";
-    };
   };
 
   hosts = {

secrets/secrets.nix

@@ -4,7 +4,6 @@ let
     keys.users.gortium.main
     keys.hosts.lazyworkhorse.main
     keys.hosts.lazyworkhorse.bootstrap
-    keys.users.hermes_agent.age
   ];
 in
 {