Use the same restic password for all machines

Since they use the same repository (for deduplication), everything else
doesn’t make sense.

modules/restic.nix

@@ -43,7 +43,7 @@ let
 in
 {
   services.restic.backups."${config.networking.hostName}-system" = {
-    passwordFile = toString (../machines/. + "/${config.networking.hostName}" + /secrets/restic_password);
+    passwordFile = toString (../secrets/restic_password);
     s3CredentialsFile = toString ../secrets/s3_credentials;
     repository = "s3:https://s3.eu-central-1.wasabisys.com/sbruder-restic";
     paths = lib.mkDefault (