Shovels: dest-uri/src-uri can be lists of URIs in 3.8

[pathcl]

Hey

It seems at some point shovel type changed for rabbit. Now for src-uri/dest-uri data types are arrays not
string anymore but []string

curl -u admin "127.0.0.1:15672/api/parameters"

[
  {
    "value": {
      "dest-add-forward-headers": true,
      "dest-add-timestamp-header": true,
      "dest-exchange": "someexchange",
      "dest-protocol": "amqp091",
      "dest-uri": [
        "amqp://user:password@server.domain.tld/tlm"
      ],
      "src-protocol": "amqp091",
      "src-queue": "somequeue",
      "src-uri": [
        "amqp://user:pass@server.domain.tld/are"
      ]
    },
    "vhost": "somevhost",
    "component": "shovel",
    "name": "someothershovel"                                                                                                                                                                                                                                  
  }                                                                                                                                                                                                                                                            
]

I realized this when I was adding support for shovels in terraformer which relies on rabbitmq provider which depends on rabbit-hole

020/12/27 14:51:11 json: cannot unmarshal array into Go struct field ShovelDefinition.value.dest-uri of type string

[michaelklishin]

Addressed in #174. Note that this is a minor breaking change to the public API.