Allow usage with zend-expressive-helpers 5.0 series

Updates the constraint for zend-expressive-helpers to include the
5.0.0-dev and/or 5.0.0 releases, as the API consumed by this package
remains compatible.

Author: weierophinney

composer.json

@@ -34,7 +34,7 @@
         "phpunit/phpunit": "^6.4.3",
         "zendframework/zend-coding-standard": "~1.0.0",
         "zendframework/zend-diactoros": "^1.6",
-        "zendframework/zend-expressive-helpers": "^4.2",
+        "zendframework/zend-expressive-helpers": "^4.2 || ^5.0.0-dev || ^5.0.0",
         "zendframework/zend-hydrator": "^2.3.1",
         "zendframework/zend-paginator": "^2.7"
     },