ci: allow zizmor action so the workflow can run #153

Description

The zizmor workflow added in #144 is currently failing before any job is created.

Affected runs end with:

startup_failure

and contain no jobs.

This also occurs on #148, which originated from nodejs/learn itself, so the failure is not specific to external pull requests.

Likely cause

nodejs/learn uses an explicit GitHub Actions allowlist. The workflow added in #146 documents that new Actions need to be approved by a maintainer with Admin permissions.

There is a direct precedent in nodejs/nodejs.org#8728: when zizmor was introduced there, maintainers confirmed that the workflow was not starting because zizmorcore/zizmor-action had not yet been added to that repository's Actions allowlist. After it was allowed, the existing zizmor workflow ran successfully.

The Learn workflow currently uses:

uses: zizmorcore/zizmor-action@3dc1ecc9bcb9e94e9b2c709687979e1298497054 # v0.6.2

Suggested fix

Could a maintainer with Admin permissions verify that zizmorcore/zizmor-action is included in this repository's allowed Actions?

After it is allowed, the existing workflow can be rerun to verify that it starts normally.

cc @nodejs/web-infra