Custom SVG logo is not displayed correctly in some mail clients

There is no validation against using SVG brand logo - uploaded via Admin=>Settings=>Navigation Bar. SVG looks fine on the website (supported by all browsers) but is not supported by some mail clients.

There are 3 approaches I can see now:

1. Validate against using an SVG file
2. Change logic to always use GitLab's logo in the email header
3. Add a separate setting to customize the email header

The bottom image is PNG file where the top one is the custom brand logo - SVG.