build(deps): bump envoyproxy/toolshed from actions-v0.1.15 to 0.1.39

Bumps [envoyproxy/toolshed](https://github.com/envoyproxy/toolshed) from actions-v0.1.15 to 0.1.39. This release includes the previously tagged commit.
- [Release notes](https://github.com/envoyproxy/toolshed/releases)
- [Commits](envoyproxy/toolshed@actions-v0.1.15...actions-v0.1.39)

---
updated-dependencies:
- dependency-name: envoyproxy/toolshed
  dependency-type: direct:production
...

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

.github/workflows/retest.yaml

@@ -22,6 +22,6 @@ jobs:
       pull-requests: write
       actions: write
     steps:
-    - uses: envoyproxy/toolshed/gh-actions/retest@actions-v0.1.15
+    - uses: envoyproxy/toolshed/gh-actions/retest@actions-v0.1.39
       with:
         token: ${{ secrets.GITHUB_TOKEN }}