Fix location of zpool command

TIL lookups are executed on the host

ansible/roles/zfs/tasks/main.yml

@@ -5,11 +5,19 @@
     mode: "0644"
   become: true
 
+- name: Locate zpool command
+  command:
+    cmd: which zpool
+    strip_empty_ends: true
+  register: which_zpool
+  changed_when: false
+  become: true
+
 - name: ZFS Scrub
   cron:
     name: scrub {{ item }} ZFS pool
     special_time: weekly
-    job: "{{ lookup('pipe', 'which zpool') }} scrub {{ item }}"
+    job: "{{ which_zpool.stdout }} scrub {{ item }}"
   become: true
   loop: "{{ zpools_to_scrub }}"