try to upgrade hercules

nix/sources.json

@@ -11,6 +11,18 @@
         "url": "https://github.com/cachix/cachix/archive/f5cd1b44c2b3dffd6cc31c56a35c55a8775acf75.tar.gz",
         "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
     },
+    "hercules-ci-agent": {
+        "branch": "master",
+        "description": "https://hercules-ci.com build and deployment agent",
+        "homepage": "",
+        "owner": "hercules-ci",
+        "repo": "hercules-ci-agent",
+        "rev": "81ad6448f41367c8ec89ee541df54419b24f4c53",
+        "sha256": "1l5jj3plhykcibfad7296j8d9bjjk6hp8ds6684077lp86dbbzgp",
+        "type": "tarball",
+        "url": "https://github.com/hercules-ci/hercules-ci-agent/archive/81ad6448f41367c8ec89ee541df54419b24f4c53.tar.gz",
+        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
+    },
     "hercules-ci-effects": {
         "branch": "add-cachix-deploy",
         "description": "Expressions to change the world",

roles/hercules-ci/default.nix

@@ -1,4 +1,4 @@
-{ config, ... }:
+{ config, pkgs, ... }:
 
 let
   herculesSecret = {
@@ -6,6 +6,7 @@ let
     sopsFile = ./secrets.yaml;
   };
   secrets = config.sops.secrets;
+  hercules = import (import ../../nix/sources.nix {}).hercules-ci-agent;
 in
 {
   sops.secrets."binary-caches.json" = herculesSecret;
@@ -14,6 +15,7 @@ in
 
   services.hercules-ci-agent = {
     enable = true;
+    package = hercules.packages.${pkgs.system}.hercules-ci-agent-nix_2_4;
     settings = {
       binaryCachesPath = secrets."binary-caches.json".path;
       secretsJsonPath = secrets."hercules-secrets".path;