bump webfactory/ssh-agent from 0.8.0 to 0.9.0

Bumps [webfactory/ssh-agent](https://github.com/webfactory/ssh-agent) from 0.8.0 to 0.9.0.
- [Release notes](https://github.com/webfactory/ssh-agent/releases)
- [Changelog](https://github.com/webfactory/ssh-agent/blob/master/CHANGELOG.md)
- [Commits](webfactory/ssh-agent@v0.8.0...v0.9.0)

---
updated-dependencies:
- dependency-name: webfactory/ssh-agent
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

.github/workflows/test.yml

@@ -22,7 +22,7 @@ jobs:
           for key in rsa ecdsa ed25519; do
             ssh-keyscan -t $key github.com 2>/dev/null >> ~/.ssh/known_hosts
           done
-      - uses: webfactory/ssh-agent@v0.8.0
+      - uses: webfactory/ssh-agent@v0.9.0
         with:
           ssh-private-key: ${{ secrets.BOT_PRIVATE_KEY }}
       - run: ./hack/setup-git-redirect.sh