Add additional permissions for backport workflow

[cdce8p]

Backporting the release workflow improvements failed. E.g. #10267

  /usr/bin/git push --set-upstream origin backport-10267-to-maintenance/3.3.x
  To https://github.com/pylint-dev/pylint.git
   ! [remote rejected]     backport-10267-to-maintenance/3.3.x -> backport-10267-to-maintenance/3.3.x (refusing to allow a GitHub App to create or update workflow `.github/workflows/release.yml` without `workflows` permission)
  error: failed to push some refs to 'https://github.com/pylint-dev/pylint.git'

https://github.com/pylint-dev/pylint/actions/runs/13748264125/job/38445990683#step:2:32

Judging by the error message, the action needs additional permissions to update workflow files.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 95.86%. Comparing base (42aa204) to head (f46af93).
Report is 116 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #10269   +/-   ##
=======================================
  Coverage   95.86%   95.86%           
=======================================
  Files         175      175           
  Lines       19068    19068           
=======================================
  Hits        18280    18280           
  Misses        788      788           

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