Bump step-security/action-slack-notify from 2.3.6 to 2.4.0 (#120)

Bumps [step-security/action-slack-notify](https://github.com/step-security/action-slack-notify) from 2.3.6 to 2.4.0.
- [Release notes](https://github.com/step-security/action-slack-notify/releases)
- [Commits](step-security/action-slack-notify@7210d1a...e4cdee1)

---
updated-dependencies:
- dependency-name: step-security/action-slack-notify
  dependency-version: 2.4.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

.github/workflows/ghaudit.yaml

@@ -52,7 +52,7 @@ jobs:
         packages: ghaudit
         command: ghaudit org -o ${{ github.repository_owner }} default-permissions
 
-    - uses: step-security/action-slack-notify@7210d1a1599b9ea84d6140184222f04f1ff56070 # v2.3.6
+    - uses: step-security/action-slack-notify@e4cdee14a905d9da46ba47ad9309704407d8cd79 # v2.4.0
       if: ${{ failure() }}
       env:
         SLACK_ICON: http://github.com/chainguard-dev.png?size=48