Why aren't banners updated in .htm Outlook signatures?

Question

Outlook

Greetings!
Installed template signatures for employees in the company.
Written in HTML, the idea is that once a week, following a link from the code in the repository, the contents of the file will change, while of course the name and path are saved.
But in Outlook, the picture does not change, despite the fact that if we take the link directly and paste it into the browser, we see a new one, as it should be.
How to solve this issue and is it possible to solve it.
Thanks to!