Resolve deprecation warning on Debian.

tasks/setup-Debian.yml

@@ -6,9 +6,8 @@
 
 - name: Ensure PostgreSQL packages are installed.
   apt:
-    name: "{{ item }}"
+    name: "{{ postgresql_packages }}"
     state: present
-  with_items: "{{ postgresql_packages }}"
 
 - name: Ensure all configured locales are present.
   locale_gen: "name={{ item }} state=present"