install:
  - composer install
language: php
php:
  - '5.4'
  - '5.5'
  - '5.6'
  - '7.0'
  - '7.1'
  - '7.2'

language: php

matrix:
  include:
    - php: 5.4
      dist: trusty
    - php: 5.5
      dist: trusty
    - php: 5.6
      dist: trusty
    - php: 7.0
      dist: trusty
    - php: 7.1
      dist: bionic
    - php: 7.2
      dist: bionic
    - php: 7.3
      dist: bionic
    - php: 7.4
      dist: bionic

install: travis_retry composer install

Add PHP 7.3 and 7.4 versions to Travis CI
Add PHP 7.3 and 7.4 versions to Travis CI

This will ensure that this project is forward compatible with them.
