Escape regex chars in ClusterImagePolicy subject

[mchmarny]

s3cme/policy/cluster.yaml

Line 13 in efa942f

subjectRegExp: "^https://github.com/mchmarny/s3cme/.github/workflows/slsa.yaml@refs/tags/v[0-9]+.[0-9]+.[0-9]+$"

[github-actions]

This issue is stale because it has been open for 90 days with no
activity. It will automatically close after 30 more days of
inactivity. Keep fresh with the 'lifecycle/frozen' label.