burp-client: Switch from cron to systemd timer

systemd timer units are supported on all relevant OS versions now.
There is no longer any reason to use cron.

roles/burp-client/tasks/main.yml

@@ -49,8 +49,28 @@
   command:
     burp -c /etc/burp/burp.conf -g
     creates=/etc/burp/ssl_cert-client.pem
-- name: ensure automatic backup is scheduled
+
+- name: ensure auto backup systemd units are installed
   copy:
-    src={{ burp_backup_crontab }}
-    dest=/etc/cron.d/burp-backup
-    mode=0644
+    src: '{{ item }}'
+    dest: /etc/systemd/system/
+    mode: u=rw,go=r
+  loop:
+  - burp-backup.service
+  - burp-backup.timer
+  notify:
+  - reload systemd
+  tags:
+  - systemd
+- name: ensure auto backup timer is enabled
+  systemd:
+    name: burp-backup.timer
+    enabled: true
+    state: started
+  tags:
+  - service
+
+- name: ensure legacy burp crontab file is removed
+  file:
+    path: /etc/cron.d/burp-backup
+    state: absent