Run AssertsTest with PHPUnit 8

Author: Naktibalda

.travis.yml

@@ -1,7 +1,7 @@
 language: php
 
 env:
-  CODECEPTION_VERSION: '2.6.x-dev'
+  CODECEPTION_VERSION: '3.0.x-dev'
 
 php:
   - 7.2
@@ -16,3 +16,4 @@ script:
   - php robo.phar test cli
   - php robo.phar test "unit -g core"
   - php robo.phar test "tests/unit/Codeception/Constraints/"
+  - php robo.phar test "tests/unit/Codeception/Module/AssertsTest.php"