Code generator for Powershell v5

I am trying to upload a file with powershell.
To do this I used Postman (form-data) to generate a powershell script like this:

add-type -AssemblyName System.Net.Http
$multipartContent = [System.Net.Http.MultipartFormDataContent]::new()
$multipartFile = 'C:\Users\hoang\Desktop\ntdll.h'
$FileStream = [System.IO.FileStream]::new($multipartFile, [System.IO.FileMode]::Open)
$fileHeader = [System.Net.Http.Headers.ContentDispositionHeaderValue]::new("form-data")
$fileHeader.Name = "file"
$fileHeader.FileName = "/C:/Users/hoang/Desktop/ntdll.h"
$fileContent = [System.Net.Http.StreamContent]::new($FileStream)
$fileContent.Headers.ContentDisposition = $fileHeader
$multipartContent.Add($fileContent)

$stringHeader = [System.Net.Http.Headers.ContentDispositionHeaderValue]::new("form-data")
$stringHeader.Name = "bla"
$stringContent = [System.Net.Http.StringContent]::new("this is test")
$stringContent.Headers.ContentDisposition = $stringHeader
$multipartContent.Add($stringContent)

$body = $multipartContent

$response = Invoke-RestMethod '172.19.183.247:5679/api/v1/upload' -Method 'POST' -Headers $headers -Body $body
$response | ConvertTo-Json

Everything looks fine (I edited the file path correctly and added System.Net.http). However on the server side I don't get any key-values or files.
After searching on google I found a workaround that is to use powershell v7. However, this version is not universal and requires additional installation.
So can you guys show me how to write a script that works with powershell v5? Or if possible, I think you guys should make postman-code-generators work with powershell v5.
Thank you very much!

Start by reproducing the generated multipart upload in PowerShell v5 using the example in the issue, then compare its behavior with PowerShell v7. Done means the generated script sends the file and form-data key-values to the stated upload endpoint and the server receives them.