PR #115 follow-up: Add missing var and add test for 20.04.

.travis.yml

@@ -9,6 +9,7 @@ env:
     - MOLECULE_DISTRO: centos7
     - MOLECULE_DISTRO: centos8
     - MOLECULE_DISTRO: fedora31
+    - MOLECULE_DISTRO: ubuntu2004
     - MOLECULE_DISTRO: ubuntu1804
     - MOLECULE_DISTRO: debian10
 

molecule/default/converge.yml

@@ -23,6 +23,7 @@
 
     - name: Update apt cache.
       apt: update_cache=true cache_valid_time=600
+      changed_when: false
       when: ansible_os_family == 'Debian'
 
     - name: Set custom variables for old CentOS 6 PostgreSQL install.

vars/Ubuntu-20.yml

@@ -8,3 +8,4 @@ __postgresql_packages:
   - postgresql
   - postgresql-contrib
   - libpq-dev
+postgresql_python_library: python3-psycopg2