Install packages from backports by default.

roles/debian_server/tasks/main.yml

@@ -15,6 +15,17 @@
     state: present
     update_cache: true
 
+- name: Set normal priority for the backports repo
+  copy:
+    content: |
+      Package: *
+      Pin: release  o=Debian Backports
+      Pin-Priority: 500
+    dest: /etc/apt/preferences.d/backports
+    group: root
+    mode: 0o644
+    owner: root
+
 - name: Install packages
   apt:
     cache_valid_time: 3600