drop 1.23/1.24 and add 1.26/27/28 k8s version and bump scaffold

[cpanato]

Summary

• drop 1.23/1.24 and add 1.26/27/28 k8s version and bump scaffold

[codecov]

Codecov Report

Merging #1063 (6bbe287) into main (ba94bf8) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main    #1063   +/-   ##
=======================================
  Coverage   54.69%   54.69%           
=======================================
  Files          44       44           
  Lines        4841     4841           
=======================================
  Hits         2648     2648           
  Misses       1977     1977           
  Partials      216      216           

[k4leung4]

we need to update the knative version
the default in the scaffolding action is 1.6.0, https://github.com/sigstore/scaffolding/blob/main/actions/setup/action.yml#L36
knative latest is 1.12.0

[cpanato]

done in another pr