upgrade to 1.26.0

Upgrade is prepaired in the branch wip-1.26.0.

Here: https://salsa.debian.org/nginx-team/nginx/-/commits/wip-1.26.0

info: @kapouer, @teward, @shankerwangmiao

Steps:

1. - package preparation
2. - upload to the experimental
3. - upload to the unstable
4. - transitions for all modules