Do not sent correct Content-Type

[glafir]

zapi = ZabbixAPI("http://zb.relef.ru/zabbix")

In zapi.session.headers "Content-Type" sending by python client is "text/html", but method update do not help for this

zapi.session.headers.update(
            {
                "Content-Type": 'application/json',
                "User-Agent": "python/pyzabbix",
                "Cache-Control": "no-cache",
            }
      )

zapi.session.header afte it return as

{'User-Agent': 'python/pyzabbix', 'Accept-Encoding': 'gzip, deflate', 'Accept': '*/*', 'Connection': 'keep-alive', 'Content-Type': 'application/json', 'Cache-Control': 'no-cache'}

But in nginx access log I see this
...,
"Content-Type":"text/html",

And I get error 412 for zabbix API, because ```Content-Type`` in nginx log recieved as ```"text/html"```

$ python -V
Python 3.8.17