Updated composer and travis files in 6.0 branch

Author: Naktibalda

.travis.yml

@@ -1,12 +1,11 @@
 language: php
 
 env:
-  CODECEPTION_VERSION: '2.4.x-dev'
+  CODECEPTION_VERSION: '2.5.x-dev'
 
 php:
   - 5.6
   - 7.0
-  - 7.1
 
 before_script:
   - wget https://robo.li/robo.phar
@@ -15,4 +14,4 @@ before_script:
 
 script:
   - php robo.phar test cli
-  - php robo.phar test "unit -g core"
+  - php robo.phar test "unit -g core"

composer.json

@@ -13,7 +13,7 @@
         "codeception/phpunit-wrapper": "*"
     },
     "require": {
-        "phpunit/phpunit": ">=5.7.27 <7.0",
+        "phpunit/phpunit": ">=5.7.27 <6.5.13",
         "phpunit/php-code-coverage": ">=4.0.4 <6.0",
         "sebastian/comparator": ">=1.2.4 <3.0",
         "sebastian/diff": ">=1.4 <4.0"