Merge pull request #194 from GrahamCampbell/patch-1

Test on PHP 5.5.9 and 7.4

.travis.yml

@@ -1,30 +1,35 @@
 language: php
 
-sudo: false
-
-dist: trusty
-
 cache:
   directories:
     - $HOME/.composer/cache/files
 
+env:
+  global:
+    - setup=basic
+
 matrix:
   include:
-    - php: 5.5
-    - php: 5.5
+    - php: 5.5.9
+      dist: trusty
       env: setup=lowest
+    - php: 5.5
+      dist: trusty
     - php: 5.6
+      dist: xenial
     - php: 7.0
-    - php: 7.0
+      dist: xenial
       env: setup=lowest
+    - php: 7.0
+      dist: xenial
     - php: 7.1
+      dist: bionic
     - php: 7.2
+      dist: bionic
     - php: 7.3
-    - php: 7.4snapshot
-
-env:
-  global:
-    - setup=basic
+      dist: bionic
+    - php: 7.4
+      dist: bionic
 
 install:
   - if [[ $setup = 'basic' ]]; then travis_retry composer install --prefer-dist --no-interaction; fi