ci: Enable users without write action to the repo to access claude review

ci: Enable users without write action to the repo to access claude review

The labelling approach introduced in 6089075265765b43e6666e4d5978292a32501496
means contributors can now trigger the workflow on their own when the label
is added by a maintainer and they update the PR. Hence we need to allow all
users to access the claude code action. This is safe because we already gate
the workflow ourselves to only the contributors that we want to allow.
Additionally, the claude code job has no permissions anymore except read access
to the repository and can execute very limited tools, so this should be safe.