Update postgres versions to latest

roles/matrix-postgres/defaults/main.yml

@@ -8,9 +8,9 @@ matrix_postgres_db_name: ""
 matrix_postgres_base_path: "{{ matrix_base_data_path }}/postgres"
 matrix_postgres_data_path: "{{ matrix_postgres_base_path }}/data"
 
-matrix_postgres_docker_image_v9: "postgres:9.6.13-alpine"
-matrix_postgres_docker_image_v10: "postgres:10.8-alpine"
-matrix_postgres_docker_image_v11: "postgres:11.3-alpine"
+matrix_postgres_docker_image_v9: "postgres:9.6.14-alpine"
+matrix_postgres_docker_image_v10: "postgres:10.9-alpine"
+matrix_postgres_docker_image_v11: "postgres:11.4-alpine"
 matrix_postgres_docker_image_latest: "{{ matrix_postgres_docker_image_v11 }}"
 
 # This variable is assigned at runtime. Overriding its value has no effect.