[Snyk] Security upgrade debian from 9.5-slim to 9-slim#264

Open

snyk-bot wants to merge 1 commit intomainfrom snyk-fix-7560ba5797e831164e8d65d2e07d1507

Commits on Jul 11, 2021

fix: content/actions/creating-actions/dockerfile-support-for-github-actions.md to reduce vulnerabilities
snyk-bot
committed