Skip prerelease versions in sync-zizmor-versions workflow (#158)

Author: Copilot

support/sync-zizmor-versions.sh

@@ -30,6 +30,11 @@ tags=$(skopeo list-tags "docker://${IMAGE}" | jq -r '.Tags[]')
 # and emit it as a line in the format:
 # <tag> <digest>
 for tag in ${tags}; do
+    # Skip prerelease versions (e.g. 1.30.0rc1, 1.30.0-beta.1)
+    # Only allow "latest" or strict MAJOR.MINOR.PATCH.
+    if [[ "${tag}" != "latest" ]] && ! [[ "${tag}" =~ ^[0-9]+\.[0-9]+\.[0-9]+$ ]]; then
+        continue
+    fi
     # Retry up to 5 times, since GHCR is unreliable.
     digest=$(skopeo --override-os=linux --override-arch=amd64 inspect --retry-times=5 "docker://${IMAGE}:${tag}" | jq -r '.Digest')
     echo "${tag} ${digest}"