Added logic and script to test for PKGBUILD poisoning

roles/arch_update/tasks/aur_upgrade.yaml

@@ -1,4 +1,8 @@
 ---
+- name: Check AUR package diffs for poisoning
+  ansible.builtin.script: aur_diff_check.py
+  changed_when: false
+
 - name: AUR upgrade
   aur:
     use: "{{ aur_helper }}"