treewide: use configured zfs package

modules/nixos/impermanence.nix

@@ -1,6 +1,5 @@
 {
   config,
-  pkgs,
   lib,
   ...
 }:
@@ -9,6 +8,7 @@ let
     mkIf
     optionals
     ;
+  zfsPkg = config.boot.zfs.package;
 in
 {
   boot.zfs.forceImportRoot = false;
@@ -24,7 +24,7 @@ in
         unitConfig.DefaultDependencies = "no";
         serviceConfig = {
           Type = "oneshot";
-          ExecStart = "${pkgs.zfs}/bin/zfs rollback -r rpool/local/root@blank";
+          ExecStart = "${zfsPkg}/bin/zfs rollback -r rpool/local/root@blank";
         };
       };
 

modules/nixos/podman.nix

@@ -1,5 +1,4 @@
 {
-  pkgs,
   lib,
   config,
   ...
@@ -9,6 +8,7 @@ with lib;
 
 let
   cfg = config.modules.podman;
+  zfsPkg = config.boot.zfs.package;
 in
 {
   options.modules.podman = {
@@ -29,7 +29,7 @@ in
           dates = "weekly";
           flags = [ "--all" ];
         };
-        extraPackages = [ pkgs.zfs ];
+        extraPackages = [ zfsPkg ];
       };
 
       containers.storage.settings.storage = {