Update .travis.yml

.travis.yml

@@ -1,10 +1,20 @@
 language: php
 
 php:
-  - 5.6
   - 7.0
   - 7.1
   - 7.2
+  - 7.3
+  - 7.4snapshot
+
+# This triggers builds to run on the new TravisCI infrastructure.
+# See: http://docs.travis-ci.com/user/workers/container-based-infrastructure/
+sudo: false
+
+## Cache composer
+cache:
+  directories:
+    - $HOME/.composer/cache
 
 sudo: false
 
@@ -13,7 +23,11 @@ cache:
   directories:
     - $HOME/.composer/cache
 
-before_script:
+matrix:
+  allow_failures:
+    - php: 7.4snapshot
+    
+install:
   - travis_retry composer install --no-interaction --prefer-dist
 
 script: