Bump rtCamp/action-slack-notify from 2.2.0 to 2.2.1 (#153)

Bumps [rtCamp/action-slack-notify](https://github.com/rtcamp/action-slack-notify) from 2.2.0 to 2.2.1.
- [Release notes](https://github.com/rtcamp/action-slack-notify/releases)
- [Commits](rtCamp/action-slack-notify@12e36fc...b24d75f)

---
updated-dependencies:
- dependency-name: rtCamp/action-slack-notify
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/release.yaml

@@ -52,7 +52,7 @@ jobs:
           path: ./serving.yaml
 
       - name: Post failure notice to Slack
-        uses: rtCamp/action-slack-notify@12e36fc18b0689399306c2e0b3e0f2978b7f1ee7 # v2.2.0
+        uses: rtCamp/action-slack-notify@b24d75fe0e728a4bf9fc42ee217caa686d141ee8 # v2.2.1
         if: ${{ failure() }}
         env:
           SLACK_ICON: http://github.com/chainguard-dev.png?size=48