[kafka] Replaced kafka dependency with kafka-python-ng.

The `kafka` module seems to be unmaintained and it's breaking apart at
initialization.

See: https://stackoverflow.com/questions/77287622/modulenotfounderror-no-module-named-kafka-vendor-six-moves-in-dockerized-djan

platypush/plugins/kafka/manifest.json

@@ -4,17 +4,11 @@
       "platypush.message.event.kafka.KafkaMessageEvent"
     ],
     "install": {
-      "apt": [
-        "python-kafka"
-      ],
-      "dnf": [
-        "python-kafka"
-      ],
       "pip": [
-        "kafka"
+        "kafka-python-ng"
       ]
     },
     "package": "platypush.plugins.kafka",
     "type": "plugin"
   }
-}
+}