Bump slackapi/slack-github-action from 1.25.0 to 1.26.0 (#4558)

Bumps [slackapi/slack-github-action](https://github.com/slackapi/slack-github-action) from 1.25.0 to 1.26.0.
- [Release notes](https://github.com/slackapi/slack-github-action/releases)
- [Commits](slackapi/slack-github-action@v1.25.0...v1.26.0)

---
updated-dependencies:
- dependency-name: slackapi/slack-github-action
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

.github/workflows/image-deps-updater.yaml

@@ -111,7 +111,7 @@ jobs:
 
       - name: Slack Notification
         if: ${{ steps.cpr.outputs.pull-request-number }}
-        uses: slackapi/slack-github-action@v1.25.0
+        uses: slackapi/slack-github-action@v1.26.0
         with: 
           payload: |
             {