updated tasks so they are only run once

tasks/pkgs/thunderbird.yml

@@ -1,13 +1,21 @@
 # vim: set filetype=yaml.ansible :
 ---
-- name: Append to pkg_sys
+- name: Add thunderbird
   when:
-    - ansible_system == 'Linux'
-  ansible.builtin.set_fact:
-    pkg_sys: "{{ pkg_sys + ['thunderbird'] }}"
+    - thunderbird_configured is undefined
+  block:
+    - name: Append to pkg_sys
+      when:
+        - ansible_system == 'Linux'
+      ansible.builtin.set_fact:
+        pkg_sys: "{{ pkg_sys + ['thunderbird'] }}"
 
-- name: Append to pkg_cask
-  when:
-    - ansible_system == 'Darwin'
-  ansible.builtin.set_fact:
-    pkg_cask: "{{ pkg_cask + ['thunderbird'] }}"
+    - name: Append to pkg_cask
+      when:
+        - ansible_system == 'Darwin'
+      ansible.builtin.set_fact:
+        pkg_cask: "{{ pkg_cask + ['thunderbird'] }}"
+
+    - name: Set thunderbird_configured
+      ansible.builtin.set_fact:
+        thunderbird_configured: true