Use precise only for php 5.3

Author: troosan

.travis.yml

@@ -1,6 +1,6 @@
 language: php
 
-dist: precise
+dist: xenial
 
 php:
     - 5.3
@@ -18,6 +18,7 @@ matrix:
         - php: 7.0
           env: COVERAGE=1
         - php: 5.3
+          dist: precise
           env: COMPOSER_MEMORY_LIMIT=2G
         - php: 7.3
           env: DEPENDENCIES="--ignore-platform-reqs"