updated tasks so they are only run once

tasks/pkgs/dust.yml

@@ -1,16 +1,24 @@
 # vim: set filetype=yaml.ansible :
 ---
-- name: Linux specific install
+- name: Add dust
   when:
-    - ansible_system == 'Linux'
-  notify:
-    - Depend cargo
-  changed_when: true
-  ansible.builtin.set_fact:
-    pkg_cargo: "{{ pkg_cargo + ['du-dust'] }}"
+    - dust_configured is undefined
+  block:
+    - name: Linux specific install
+      when:
+        - ansible_system == 'Linux'
+      notify:
+        - Depend cargo
+      changed_when: true
+      ansible.builtin.set_fact:
+        pkg_cargo: "{{ pkg_cargo + ['du-dust'] }}"
 
-- name: Append to pkg_sys
-  when:
-    - ansible_os_family == 'Darwin'
-  ansible.builtin.set_fact:
-    pkg_sys: "{{ pkg_sys + ['dust'] }}"
+    - name: Append to pkg_sys
+      when:
+        - ansible_os_family == 'Darwin'
+      ansible.builtin.set_fact:
+        pkg_sys: "{{ pkg_sys + ['dust'] }}"
+
+    - name: Set dust_configured
+      ansible.builtin.set_fact:
+        dust_configured: true