Switch to the latest version of Forgejo Next

[betulependule]

We are using Forgejo Next v10 to host our testing repos. However, v10 reached its end of life with the release of Forgejo v11.0 on the 16th of April 2025. For that reason, we should switch to the latest version of Forgejo Next.

[LecrisUT]

This is actually a blocker for adding new tests now because the certificates in https://v10.next.forgejo.org are expired now