Bump hashicorp/actions-slack-status from 1 to 2

Bumps [hashicorp/actions-slack-status](https://github.com/hashicorp/actions-slack-status) from 1 to 2.
- [Release notes](https://github.com/hashicorp/actions-slack-status/releases)
- [Commits](hashicorp/actions-slack-status@v1...v2)

---
updated-dependencies:
- dependency-name: hashicorp/actions-slack-status
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

.github/workflows/update-helm-charts-index.yml

@@ -31,7 +31,7 @@ jobs:
             --ref main \
             -f SOURCE_TAG="${{ github.ref_name }}" \
             -f SOURCE_REPO="${{ github.repository }}"
-      - uses: hashicorp/actions-slack-status@v1
+      - uses: hashicorp/actions-slack-status@v2
         if: ${{always()}}
         with:
           success-message: "vault-helm charts index update triggered successfully. View the run <https://github.com/hashicorp/helm-charts/actions/workflows/publish-charts.yml|here>."