Merge pull request MyIntervals#157 from sabberworm/update-tested-php-versions

Test with PHP 7.2 and 7.3 release but not 8 nightly as that fails currently

Author: sabberworm

.travis.yml

@@ -5,7 +5,8 @@ php:
     - "5.6"
     - "7.0"
     - "7.1"
-    - "nightly"
+    - "7.2"
+    - "7.3"
     - hhvm
 sudo: false
 dist: trusty