Fix travis build

.travis.yml

@@ -1,12 +1,17 @@
 language: php
 
-php:
+matrix:
-  - 5.4
+  fast_finish: true
-  - 5.5
+  include:
-  - 5.6
+    - php: "7.3"
-  - 7.0
+    - php: "7.2"
-  - 7.1
+    - php: "7.1"
-#  - hhvm
+    - php: "7.0"
+    - php: "5.6"
+    - php: "5.5"
+      dist: trusty
+    - php: "5.4"
+      dist: trusty
 
 # faster builds on new travis setup not using sudo
 sudo: false