Fix lint warning about non-FQCN ansible.builtin.user

Seems ansible-lint thinks a task calling the unqualified user module is
"not valid under any of the given schemas (schema[tasks])".

roles/archusers/tasks/main.yml

@@ -8,7 +8,7 @@
   with_dict: "{{ arch_users }}"
 
 - name: Create Arch Linux-specific users
-  user:
+  ansible.builtin.user:
     name: "{{ item.key }}"
     group: users
     groups: "{{ item.value.groups | join(',') }}"

roles/borg_server/tasks/main.yml

@@ -2,7 +2,7 @@
   pacman: name=borg state=present
 
 - name: Create borg user
-  user:
+  ansible.builtin.user:
     name: borg
     home: "{{ backup_dir }}"
 

roles/dbscripts/tasks/main.yml

@@ -39,7 +39,7 @@
     - nginx
 
 - name: Create Arch Linux-specific users
-  user:
+  ansible.builtin.user:
     name: "{{ item.key }}"
     group: users
     groups: "{{ item.value.groups | join(',') }}"

roles/postfix_null/tasks/main.yml

@@ -11,7 +11,7 @@
 
 - name: Create user account on mail to relay with
   delegate_to: mail.archlinux.org
-  user:
+  ansible.builtin.user:
     name: "{{ inventory_hostname_short }}"
     comment: "SMTP Relay Account for {{ inventory_hostname }}"
     group: nobody