ossupstream.org is gone - remove reference to it?

[maxandersen]

Describe the bug

There are links to ossupstream.org which is no longer active.

should remove references to it in https://github.com/quarkusio/quarkusio.github.io/blob/50eaff2c8c632e3bbd70d9ed1f4d0c90290273f1/_layouts/base.html#L34 and https://github.com/quarkusio/quarkusio.github.io/blob/50eaff2c8c632e3bbd70d9ed1f4d0c90290273f1/_layouts/base.html#L72