[StepSecurity] ci: Harden GitHub Actions (#597)

## Summary

This pull request is created by
[StepSecurity](https://app.stepsecurity.io/securerepo) at the request of
@bigdaz. Please merge the Pull Request to incorporate the requested
changes. Please tag @bigdaz on your message if you have any questions
related to the PR.
## Security Fixes

### Pinned Dependencies

GitHub Action tags and Docker tags are mutable. This poses a security
risk. GitHub's Security Hardening guide recommends pinning actions to
full length commit.

- [GitHub Security
Guide](https://docs.github.com/en/actions/security-guides/security-hardening-for-github-actions#using-third-party-actions)
- [The Open Source Security Foundation (OpenSSF) Security
Guide](https://github.com/ossf/scorecard/blob/main/docs/checks.md#pinned-dependencies)


## Feedback
For bug reports, feature requests, and general feedback; please email
support@stepsecurity.io. To create such PRs, please visit
https://app.stepsecurity.io/securerepo.


Signed-off-by: StepSecurity Bot <bot@stepsecurity.io>

Signed-off-by: StepSecurity Bot <bot@stepsecurity.io>

.github/workflows/integ-test-dependency-graph.yml

@@ -178,7 +178,7 @@ jobs:
     runs-on: "ubuntu-latest"
     steps:
     - name: Download dependency-graph artifact
-      uses: actions/download-artifact@v4
+      uses: actions/download-artifact@95815c38cf2ff2164869cbab79da8d1f422bc89e # v4.2.1
       with:
         path: downloaded-dependency-graphs
         pattern: dependency-graph_*dependency-graph-generate-submit-and-upload.json