upd spec version.

Author: makasim

composer.json

@@ -19,7 +19,7 @@
     "phpunit/phpunit": "~5.4.0",
     "symfony/dependency-injection": "^4",
     "symfony/config": "^4",
-    "queue-interop/queue-spec": "^0.5.5@dev",
+    "queue-interop/queue-spec": "0.6.x-dev",
     "enqueue/test": "0.9.x-dev",
     "enqueue/enqueue": "0.9.x-dev",
     "enqueue/null": "0.9.x-dev"