Use new style of calling apt in ansible

roles/common/tasks/main.yml

     - dependencies
 
 - name: Install necessities and nice-to-haves
-  apt: pkg={{ item }} state=present
-  with_items:
+  apt:
+    name: "{{ packages }}"
+    state: present
+  vars:
+    packages:
     - apache2
     - apt-transport-https
     - apticron

roles/common/tasks/postgres.yml

 # Defines tasks applicable for postgreSQL
 
 - name: Install Postgres
-  apt: pkg={{ item }} state=present
-  with_items:
+  apt:
+    name: "{{ packages }}"
+    state: present
+  vars:
+    packages:
     - postgresql
     - python-psycopg2
   tags:

roles/common/tasks/security.yml

 - name: Install security-related packages
-  apt: pkg={{ item }} state=present
-  with_items:
+  apt:
+    name: "{{ packages }}"
+    state: present
+  vars:
+    packages:
     - fail2ban
     - whois
     - lynis