fix: broker 'UNSUPPORTED_VERSION' problem arising from 'api_version'

[Niubility-Wen]

Hello, I am having some problems sending messages to different versions of kafka:

1. test dev: opresty-1.21.4.3 + kafka 3.7.0 + lua-resty-kafka latest

• Do not set 'api_version' in 'client_config'
• All is well

2. pro dev: opresty-1.21.4.3 + kafka 1.1.0 + lua-resty-kafka latest

• An 'UNSUPPORTED_VERSION' error is reported regardless of whether the 'api_version' in 'client_config' is set to 0, 1, or 2

I found that the 'api_version' parameter in line 49 and 118 of client.lua is hard code

local function metadata_encode(client_id, topics, num)
    local id = 0    -- hard code correlation_id
    local req = request:new(request.MetadataRequest, id, client_id, request.API_VERSION_V1)

    req:int32(num)

    for i = 1, num do
        req:string(topics[i])
    end

    return req
end

local function api_versions_encode(client_id)
    local id = 1    -- hard code correlation_id
    return request:new(request.ApiVersionsRequest, id, client_id, request.API_VERSION_V2)
end

I have made some changes to client.lua to achieve better compatibility between client and broker

[yuqiquan]

I also encountered the same issue with Kafka version 1.x. By modifying the code as described above and setting api_version to 1, I was able to send messages to Kafka normally. As of today, it seems the latest version 0.23 has not adopted this code. I'm a bit confused now:

1. What problems might arise from this change, and why hasn't it been adopted?
2. Why are the versions hardcoded in some places within client.lua, with one being v1 and another being v2?

Please help me understand this, thank you.