build(deps): Bump envoyproxy/toolshed from actions-v0.1.83 to 0.2.18

Bumps [envoyproxy/toolshed](https://github.com/envoyproxy/toolshed) from actions-v0.1.83 to 0.2.18. This release includes the previously tagged commit.
- [Release notes](https://github.com/envoyproxy/toolshed/releases)
- [Commits](envoyproxy/toolshed@actions-v0.1.83...actions-v0.2.18)

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

Signed-off-by: dependabot[bot] <[email protected]>

.github/workflows/envoy-sync.yaml

@@ -22,7 +22,7 @@ jobs:
       }}
     steps:
     - id: appauth
-      uses: envoyproxy/toolshed/gh-actions/appauth@actions-v0.1.83
+      uses: envoyproxy/toolshed/gh-actions/appauth@actions-v0.2.18
       with:
         key: ${{ secrets.ENVOY_CI_UPDATE_BOT_KEY }}
         app_id: ${{ secrets.ENVOY_CI_UPDATE_APP_ID }}