Add PHP 7.3 and 7.4 to the matrix

Author: lcobucci

.travis.yml

@@ -4,6 +4,8 @@ language: php
 
 php:
   - 7.2
+  - 7.3
+  - 7.4snapshot
   - nightly
 
 cache:
@@ -21,6 +23,7 @@ script:
 
 jobs:
   allow_failures:
+    - php: 7.4snapshot
     - php: nightly
 
   include: