Drop more versions of dependencies

Author: Nyholm

composer.json

@@ -20,9 +20,9 @@
     "require-dev": {
         "doctrine/instantiator": "^1.1",
         "guzzlehttp/psr7": "^1.4",
-        "phpspec/phpspec": "^3.4 || ^4.2",
+        "phpspec/phpspec": "^5.1",
         "phpspec/prophecy": "^1.8",
-        "sebastian/comparator": "^2.1.3 || ^3.0"
+        "sebastian/comparator": "^3.0"
     },
     "suggest": {
         "ext-json": "To detect JSON responses with the ContentTypePlugin",