Manifest v3 inject script from popup.js

In manifest v2 this code worked and injected the script when button was clicked:

popup.js v2 (works)

document.addEventListener('DOMContentLoaded', function () {
// Get Scan button by ID
var scanButton = document.getElementById('btnScan');

// Define Scan button on click action
scanButton.onclick = function () {
    chrome.tabs.executeScript(null, {
        file: 'Scripts/script.js'
    });
    window.close();
    }
});

Now in manifest v3, chrome.tabs.executeScript is replaced with chrome.scripting.executeScript.

scripting permission is added in manifest.json.

popup.js v3 ()

document.addEventListener('DOMContentLoaded', function () {
// Get Scan button by ID
var scanButton = document.getElementById('btnScan');

// Define Scan button on click action
scanButton.onclick = function () {
    chrome.scripting.executeScript
        (
        {
            target: { tabId: null}, // ???????
            files: ['Scripts/script.js']
        }
        );
    window.close();
    }
});

The problem is that chrome.tabs.executeScript requires tabId value as one of the parameters.
How can I get tabId value in popup.js or convert the manifest v2 version javascript so that it works the same?