AWS Signatures with pm.sendrequest

This is an old thread, but incase anybody finds it and has a similar need here is a solution that worked for me that got posted here

pm.sendRequest({
    url: "https://ssm.eu-central-1.amazonaws.com",
    method: "POST",
    header: {
        'Content-Type': 'application/x-amz-json-1.1',
        'X-Amz-Target': 'AmazonSSM.GetParameter'
    },
    auth: {
        type: "awsv4",
        "awsv4": {
            "accessKey": "$ACCESSKEY",
            "secretKey": "$SECRET",
            "region": "eu-central-1",
            "service": "ssm",
            "sessionToken": "$SESSION_TOKEN"
        }
    },
    body: .....
}, function (err, response) {
    ....
});