HTTP.jl’s API is different from Python’s requests. In particular, HTTP.request (post is a convenience method for request), doesn’t know the keyword arguments files and headers.
Instead it is called as HTTP.post(url, headers, body).
I believe something like
body = HTTP.Form(Dict(:file => fileOpened))
would do the trick. See API Reference · HTTP.jl
Your headers seem fine, but maybe you need to declare
Content-Type => multipart/form-data
No guarantees though, I’m not an expert.