DOCSP-40474 dark mode image update

[kyuan-mongodb]

Updated the landing page image to comply with dark mode. (see JIRA ticket for more info)

• JIRA
• Staging
• Build

[davidhou17]

Sorry you'll also need to export the image as an SVG file, not just change the extension:

[docs-builder-bot]

✨ Staging URL: https://preview-mongodbmongodb.gatsbyjs.io/bi-connector/master/

🪵 Logs

• job log: fb1c86eb3dbc137fc193e25b2182fdeaba198280