Allow rdkafka v6 (#33)

Author: simPod

composer.json

@@ -15,7 +15,7 @@
     "require": {
         "php": "^8.0",
         "ext-pcntl": "*",
-        "ext-rdkafka": "^5",
+        "ext-rdkafka": "^5 || ^6",
         "psr/log": "^1.1 || ^2 || ^3"
     },
     "require-dev": {