ci: add Zizmor workflow

Zizmor (https://docs.zizmor.sh/) is a static analysis tool for GitHub
Actions. Most of the issues identified by Zizmor were fixed in #27642.
This Zizmor action integrates with GitHub Advanced Security and scans
workflows for potential security issues, which should help ensure that
such issues aren't reintroduced in the future.

Signed-off-by: Daniel Hast <[email protected]>