Fix for tests

Author: gizburdt

.travis.yml

@@ -1,17 +1,18 @@
 language: php
 
 php:
-  - 5.6
-  - 7.0
-  - 7.1
+  - 7.2
+  - 7.3
 
 env:
-  matrix:
-    - COMPOSER_FLAGS="--prefer-lowest"
-    - COMPOSER_FLAGS=""
+  - LARAVEL_VERSION=5.7.*
+  - LARAVEL_VERSION=5.8.*
+  - LARAVEL_VERSION=^6.0
+  - LARAVEL_VERSION=^7.0
 
 before_script:
   - travis_retry composer self-update
+  - composer require laravel/framework:${LARAVEL_VERSION}
   - travis_retry composer update ${COMPOSER_FLAGS} --no-interaction --prefer-source
 
 script: