Hi Tomasz,
These are the default headers (they come from the underlying python requests module.
First thing I’d try is define the headers you don’t want with a value of None, with a bit of luck that will un-define them 
I’ve never done it but if you use PUT On Session you may be able to use Update Session to remove them before the PUT.
If you are using PUT, maybe not because the requests module creates a temporary session to make the PUT call, and that temporary session creates the default headers.
I found this example of removing the default headers in python for the requests module, so it’s possible in the underlying code, just not sure if there’s anything implemented in this library.
Hopefully some else can give you a better answer,
Dave.