Need PHPUnit 4 for older PHP versions

Author: DougSisk

composer.json

@@ -19,7 +19,7 @@
         "orchestra/testbench": "^3.0",
         "mockery/mockery": "^0.9",
         "satooshi/php-coveralls": "^1.0",
-        "phpunit/phpunit": "~5.0"
+        "phpunit/phpunit": "~4.0|~5.0"
     },
     "autoload": {
         "psr-4": {