Automate post api by uploading (xlsx or csv or xml file) via robotFramework

I am getting a HTTPError: 400 Client Error: Bad Request for url ; when I run the following robot test case which aims to automate POST api. I have no issue when I run the api via postman by uploading an xlsx file in the body then running the api

*** Settings ***
Library   RequestsLibrary
Library   OperatingSystem
Library   Collections

*** Variables ***
${FILE_PATH}   path-to-my-file/products.xlsx

*** Test Cases ***
Upload XLSX File Test
    [Documentation]    Upload XLSX file with parameters and verify 201 response
    ${file}=   Get File For Streaming Upload   ${FILE_PATH}
    ${files}=   Create Dictionary   file=${file}   operator_format=false   Content-Type=multipart/form-data
    ${headers}=   Create Dictionary   Authorization=xxxxxxxxxxxxxxxxxxxxxxxxxxx   Accept=application/json    Content-Type=multipart/form-data    
    Create Session   mySession   ${API_URL}   verify=false
    ${response}=   POST On Session   mySession   /api/products/imports   headers=${headers}   data=${files}
    Should Be Equal As Strings    ${response.status_code}    201