nixos: services: paperless: use 'environmentFile'

That way I don't have to configure all services to make use of it.

Someday I'll find the will to add the `postgresql.service` dependency
upstream, truly removing the need to configure any service at all.

flake.lock

@@ -136,11 +136,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1732025103,
+        "lastModified": 1732482255,
-        "narHash": "sha256-qjEI64RKvDxRyEarY0jTzrZMa8ebezh2DEZmJJrpVdo=",
+        "narHash": "sha256-GUffLwzawz5WRVfWaWCg78n/HrBJrOG7QadFY6rtV8A=",
         "owner": "nix-community",
         "repo": "home-manager",
-        "rev": "a46e702093a5c46e192243edbd977d5749e7f294",
+        "rev": "a9953635d7f34e7358d5189751110f87e3ac17da",
         "type": "github"
       },
       "original": {
@@ -152,11 +152,11 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1732014248,
+        "lastModified": 1732521221,
-        "narHash": "sha256-y/MEyuJ5oBWrWAic/14LaIr/u5E0wRVzyYsouYY3W6w=",
+        "narHash": "sha256-2ThgXBUXAE1oFsVATK1ZX9IjPcS4nKFOAjhPNKuiMn0=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "23e89b7da85c3640bbc2173fe04f4bd114342367",
+        "rev": "4633a7c72337ea8fd23a4f2ba3972865e3ec685d",
         "type": "github"
       },
       "original": {
@@ -168,11 +168,11 @@
     },
     "nur": {
       "locked": {
-        "lastModified": 1732131502,
+        "lastModified": 1732704680,
-        "narHash": "sha256-kWc3mjgEUh+2xzaluNxLMvEHRkfJ37pRBtXcwekKefM=",
+        "narHash": "sha256-x3NlO2qzuobU9BrynzydX7X9oskJpysv7BI7DJ5cVSE=",
         "owner": "nix-community",
         "repo": "NUR",
-        "rev": "13b44543c4e5d20bb2976ddde846c7341e4c41dd",
+        "rev": "31a30f0862fd8b5f88a6597382bb09197356b19e",
         "type": "github"
       },
       "original": {

modules/nixos/services/paperless/default.nix

@@ -84,43 +84,30 @@ in
 
       # Admin password
       passwordFile = cfg.passwordFile;
+
+      # Secret key
+      environmentFile = cfg.secretKeyFile;
     };
 
     systemd.services = {
       paperless-scheduler = {
         requires = [ "postgresql.service" ];
         after = [ "postgresql.service" ];
-
-        serviceConfig = {
-          EnvironmentFile = cfg.secretKeyFile;
-        };
       };
 
       paperless-consumer = {
         requires = [ "postgresql.service" ];
         after = [ "postgresql.service" ];
-
-        serviceConfig = {
-          EnvironmentFile = cfg.secretKeyFile;
-        };
       };
 
       paperless-web = {
         requires = [ "postgresql.service" ];
         after = [ "postgresql.service" ];
-
-        serviceConfig = {
-          EnvironmentFile = cfg.secretKeyFile;
-        };
       };
 
       paperless-task-queue = {
         requires = [ "postgresql.service" ];
         after = [ "postgresql.service" ];
-
-        serviceConfig = {
-          EnvironmentFile = cfg.secretKeyFile;
-        };
       };
     };