Merge pull request #21 from sunrise-php/renovate/phpunit-phpunit-7.x

Update dependency phpunit/phpunit to v7.5.13

Author: fenric

composer.json

@@ -31,7 +31,7 @@
         "php": "^7.1"
     },
     "require-dev": {
-        "phpunit/phpunit": "7.5.6",
+        "phpunit/phpunit": "7.5.13",
         "phpunit/php-code-coverage": "6.1.4",
         "sunrise/coding-standard": "1.0.0"
     },